由于某些MSP不匹配，对等方无法加入频道

分类：编程问答

如何解决由于某些MSP不匹配，对等方无法加入频道

问题

我正在尝试创建一个具有两个组织和一个渠道的网络。来自第一个组织的对等方毫无问题地加入了渠道，但是当我尝试将来自第二个组织的对等方添加到渠道时，我在其日志中得到此错误：

2020-08-12 18:53:08.351 UTC [endorser] Validate -> WARN 110 access denied: channel expected MSP ID RegulatorMSP,received BrokerMSP channel= txID=5096f00a

2020-08-12 18:53:08.351 UTC [comm.grpc.server] 1 -> INFO 111 unary call completed grpc.service=protos.Endorser grpc.method=ProcessProposal grpc.peer_address=172.23.0.1:36922 error="error validating proposal: access denied: channel [] creator org [BrokerMSP]" grpc.code=Unknown grpc.call_duration=5.7274ms

过去8个小时，我一直在摆弄配置以查找错误，但结果却很短，这使我发疯。

配置

这是我用来启动网络的脚本：

DOCK_FOLDER=$PWD
echo '[=======================================================]'
echo '[============== A: Set up the environment ==============]'
echo '[=======================================================]'
echo '[==================== A.1: Cleanup =====================]'
./clean.sh all # this just kills docker containers and cleans up hlf artifacts
cd config

echo ''
echo '[================= A.2: Crypto Config =================]'
cryptogen generate --config=crypto-config.yaml
export FABRIC_CFG_PATH=$PWD

echo ''
echo '[=============== A.3: Block Generation ================]'
configtxgen -outputBlock  ./orderer/genesis.block -channelID ordererchannel  -profile CompOrdererGenesis

echo ''
echo '[============= A.4: Transaction Generation ============]'
configtxgen -outputCreateChannelTx  compchannel.tx -channelID compchannel  -profile CompChannel

cd $DOCK_FOLDER

echo ''
echo '[================= A.5: Docker Compose ================]'
docker-compose -f ./config/docker-compose-base.yaml up -d

echo ''
echo '[=============== A.6: Initialize CouchDB ==============]'
sleep 5

curl -X PUT <username>:<password>@couchdb.regulator.com:5984/_users
curl -X PUT <username>:<password>@couchdb.regulator.com:5984/_replicator
curl -X PUT <username>:<password>@couchdb.regulator.com:5984/_global_changes

curl -X PUT <username>:<password>@couchdb.broker.com:6984/_users
curl -X PUT <username>:<password>@couchdb.broker.com:6984/_replicator
curl -X PUT <username>:<password>@couchdb.broker.com:6984/_global_changes

sleep 10

echo ''
echo '[=======================================================]'
echo '[=========== B. Manage the network: Regulator ==========]'
echo '[=======================================================]'
echo '[========== B.1: Set context to Regulator org ==========]'
export ORG_CONTEXT="regulator"
export ORG_NAME="Regulator"
export CORE_PEER_LOCALMSPID="RegulatorMSP"
export FABRIC_LOGGING_SPEC=INFO
export FABRIC_CFG_PATH=$PWD/config/regulator
export CORE_PEER_ADDRESS=peer.regulator.com:7051
export CORE_PEER_MSPCONFIGPATH=$PWD/config/crypto-config/peerOrganizations/regulator.com/users/Admin@regulator.com/msp
export ORDERER_ADDRESS=orderer.regulator.com:7050

echo ''
echo '[========== B.2: Create compchannel channel ==========]'
peer channel create -c compchannel -f ./config/compchannel.tx --outputBlock ./config/compchannel.block -o $ORDERER_ADDRESS
sleep 10s

echo ''
echo '[====== B.3: Join regulator peer to compchannel ======]'
peer channel join -b ./config/compchannel.block -o $ORDERER_ADDRESS
sleep 10s

echo ''
echo '[================= B.4: Update anchors =================]'
PEER_FABRIC_CFG_PATH=$FABRIC_CFG_PATH
FABRIC_CFG_PATH=./config
configtxgen -outputAnchorPeersUpdate ./config/peer-update.tx   -asOrg $ORG_NAME -channelID compchannel  -profile CompChannel
FABRIC_CFG_PATH=$PEER_FABRIC_CFG_PATH
peer channel update -f ./config/peer-update.tx -c compchannel -o $ORDERER_ADDRESS
sleep 10s

echo ''
echo '[=======================================================]'
echo '[============ C. Manage the network: Broker ============]'
echo '[=======================================================]'
echo '[=========== C.1: Set context to Broker org ============]'
export ORG_CONTEXT="broker"
export ORG_NAME="Broker"
export CORE_PEER_LOCALMSPID="BrokerMSP"
export FABRIC_LOGGING_SPEC=INFO
export FABRIC_CFG_PATH=$PWD/config/broker
export CORE_PEER_ADDRESS=peer.broker.com:8051
export CORE_PEER_MSPCONFIGPATH=$PWD/config/crypto-config/peerOrganizations/broker.com/users/Admin@broker.com/msp
export ORDERER_ADDRESS=orderer.regulator.com:7050


echo ''
echo '[======== C.3: Join broker peer to compchannel =======]'
peer channel join -b ./config/compchannel.block -o $ORDERER_ADDRESS  ### !!! THIS STEP FAILS !!!
sleep 10s

echo ''
echo '[================= C.4: Update anchors =================]'
PEER_FABRIC_CFG_PATH=$FABRIC_CFG_PATH
FABRIC_CFG_PATH=./config
configtxgen -outputAnchorPeersUpdate ./config/peer-update.tx -asOrg $ORG_NAME -channelID compchannel  -profile CompChannel
FABRIC_CFG_PATH=$PEER_FABRIC_CFG_PATH
peer channel update -f ./config/peer-update.tx -c compchannel -o $ORDERER_ADDRESS

orderer / orderer.yaml 

    General:
    BootstrapMethod: file
    BootstrapFile: /var/hyperledger/config/genesis.block

    BCCSP:
        Default: SW
        SW:
            HASH: SHA2
            Security: 256
            FileKeyStore:
                Keystore:

    LocalMSPDir: /var/hyperledger/msp
    LocalMSPID: OrdererMSP
    ListenAddress: 0.0.0.0
    ListenPort: 7050

    Cluster:
        SendBufferSize: 10
        ClientCertificate:
        ClientPrivateKey:
        ListenPort:
        ListenAddress:
        ServerCertificate:
        ServerPrivateKey:

    Keepalive:
        ServerMinInterval: 60s
        ServerInterval: 7200s
        ServerTimeout: 20s

    TLS:
        Enabled: false
        PrivateKey: ./server.key
        Certificate: ./server.crt
        RootCAs:
          - ./ca.crt
        ClientAuthRequired: false
        ClientRootCAs:

FileLedger:
    Location: /var/ledger
    Prefix: hyperledger-fabric-ordererledger    

Debug:
    BroadcastTraceDir:
    DeliverTraceDir:

Operations:
    ListenAddress: 127.0.0.1:8443

    TLS:
        Enabled: false
        Certificate:
        PrivateKey:
        ClientAuthRequired: false
        RootCAs: []

Metrics:
    Provider: disabled

    Statsd:
      Network: udp
      Address: 127.0.0.1:8125
      WriteInterval: 30s
      Prefix:

Consensus:
    WALDir: /var/hyperledger/production/orderer/etcdraft/wal
    SnapDir: /var/hyperledger/production/orderer/etcdraft/snapshot

regulator / core.yaml （经纪人/core.yaml几乎相同，只是将监管机构换成经纪人）

    peer:
    id: peer.regulator.com
    networkId: dev
    listenAddress: 0.0.0.0:7051
    address: 0.0.0.0:7051
    addressAutoDetect: false
    gomaxprocs: -1

    keepalive:
        minInterval: 60s

        client:
            interval: 60s
            timeout: 20s

        deliveryClient:
            interval: 60s
            timeout: 20s

    gossip:
        bootstrap:
        useLeaderElection: false
        orgLeader: true
        membershipTrackerInterval: 5s
        endpoint:
        maxBlockCountToStore: 100
        maxPropagationBurstLatency: 10ms
        maxPropagationBurstSize: 10
        propagateIterations: 1
        propagatePeerNum: 3
        pullInterval: 4s
        pullPeerNum: 3
        requestStateInfoInterval: 4s
        publishStateInfoInterval: 4s
        stateInfoRetentionInterval:
        publishCertPeriod: 10s
        skipBlockVerification: false
        dialTimeout: 3s
        connTimeout: 2s
        recvBuffSize: 20
        sendBuffSize: 200
        digestWaitTime: 1s
        requestWaitTime: 1500ms
        responseWaitTime: 2s
        aliveTimeInterval: 5s
        aliveExpirationTimeout: 25s
        reconnectInterval: 25s
        externalEndpoint: peer.regulator.com:7051

        election:
            startupGracePeriod: 15s
            membershipSampleInterval: 1s
            leaderAliveThreshold: 10s
            leaderElectionDuration: 5s

        pvtData:
            pullRetryThreshold: 60s
            transientstoreMaxBlockRetention: 1000
            pushAckTimeout: 3s
            btlPullMargin: 10
            reconcileBatchSize: 10
            reconcileSleepInterval: 1m
            reconciliationEnabled: true

    tls:
        enabled: false
        clientAuthRequired: false

        cert:
            file: tls/server.crt

        key:
            file: tls/server.key

        rootcert:
            file: tls/ca.crt

        clientRootCAs:
            files:
                - tls/ca.crt

        clientKey:
            file:

        clientCert:
            file:

    authentication:
        timewindow: 15m

    fileSystemPath: /var/hyperledger/production

    BCCSP:
        Default: SW

        SW:
            Hash: SHA2
            Security: 256

            FileKeyStore:
                KeyStore:

        PKCS11:
            Library:
            Label:
            Pin:
            Hash:
            Security:
            FileKeyStore:
                KeyStore:

    mspConfigPath: /var/hyperledger/msp
    localMspId: RegulatorMSP

    client:
        connTimeout: 3s

    deliveryclient:
        reconnectTotalTimeThreshold: 3600s
        connTimeout: 3s
        reConnectBackoffThreshold: 3600s

    localMspType: bccsp

    profile:
        enabled: false
        listenAddress: 0.0.0.0:6060

    adminService:

    handlers:
        authFilters:
            - name: DefaultAuth
            - name: ExpirationCheck

        decorators:
            - name: DefaultDecorator

        endorsers:
            escc:
                name: DefaultEndorsement
                library:
                
        validators:
            vscc:
                name: DefaultValidation
                library:

    validatorPoolSize:

    discovery:
        enabled: true
        authCacheEnabled: true
        authCacheMaxSize: 1000
        authCachePurgeRetentionRatio: 0.75
        orgMembersAllowedAccess: false

vm:
    endpoint: unix:///var/run/docker.sock

    docker:
        tls:
            enabled: false
            ca:
                file: docker/ca.crt

            cert:
                file: docker/tls.crt

            key:
                file: docker/tls.key

        attachStdout: false

        hostConfig:
            NetworkMode: host
            Dns:
                # - 192.168.0.1
            LogConfig:
                Type: json-file
                Config:
                    max-size: "50m"
                    max-file: "5"
            Memory: 2147483648

chaincode:
    id:
        path:
        name:

    builder: $(DOCKER_NS)/fabric-ccenv:$(TWO_DIGIT_VERSION)
    pull: false

    golang:
        runtime: $(DOCKER_NS)/fabric-baseos:$(TWO_DIGIT_VERSION)
        dynamicLink: false

    java:
        runtime: $(DOCKER_NS)/fabric-javaenv:$(TWO_DIGIT_VERSION)

    node:
        runtime: $(DOCKER_NS)/fabric-nodeenv:$(TWO_DIGIT_VERSION)

    externalBuilders: []
    installTimeout: 300s
    startuptimeout: 300s
    executetimeout: 30s
    mode: net
    keepalive: 0

    system:
        _lifecycle: enable
        cscc: enable
        lscc: enable
        escc: enable
        vscc: enable
        qscc: enable

    logging:
        level: info
        shim: warning
        format: "%{color}%{time:2006-01-02 15:04:05.000 MST} [%{module}] %{shortfunc} -> %{level:.4s} %{id:03x}%{color:reset} %{message}"

ledger:
    blockchain:

    state:
        stateDatabase: CouchDB
        totalQueryLimit: 100000

        couchDBConfig:
            couchDBAddress: couchdb.regulator.com:5984
            username: <username>
            password: <password>
            maxRetries: 3
            maxRetriesOnStartup: 20
            requestTimeout: 35s
            internalQueryLimit: 1000
            maxBatchUpdateSize: 1000
            warmIndexesAfterNBlocks: 1
            createGlobalChangesDB: false

    history:
        enableHistoryDatabase: true

    pvtdataStore:
        collElgProcMaxDbBatchSize: 5000
        collElgProcDbBatchesInterval: 1000

operations:
    listenAddress: 127.0.0.1:9443

    tls:
        enabled: false

        cert:
            file:

        key:
            file:

        clientAuthRequired: false

        clientRootCAs:
            files: []

metrics:
    provider: disabled

    statsd:
        network: udp
        address: 127.0.0.1:8125
        writeInterval: 10s
        prefix:

configtx.yaml 

Capabilities:
  Application: &ApplicationCapabilities
    V2_0: true
  Orderer: &OrdererCapabilities
    V2_0: true
  Channel: &ChannelCapabilities
    V2_0: true

Organizations:
  - &Orderer
    Name: Orderer
    ID: OrdererMSP
    MSPDir: ./crypto-config/ordererOrganizations/regulator.com/msp
    
    Policies: &OrdererPolicies
      Readers:
          Type: Signature
          Rule: "OR('OrdererMSP.member')"
      Writers:
          Type: Signature
          Rule: "OR('OrdererMSP.member')"
      Admins:
          Type: Signature
          
          Rule: "OR('OrdererMSP.admin')"
      Endorsement:
          Type: Signature
          Rule: "OR('OrdererMSP.member')"

  - &Regulator
    Name: Regulator
    ID: RegulatorMSP
    MSPDir: ./crypto-config/peerOrganizations/regulator.com/msp
    Policies: &RegulatorPolicies
      Readers:
          Type: Signature
          Rule: "OR('RegulatorMSP.member')"
      Writers:
          Type: Signature
          Rule: "OR('RegulatorMSP.member')"
      Admins:
          Type: Signature
          Rule: "OR('RegulatorMSP.admin')"
      Endorsement:
          Type: Signature
          
          Rule: "OR('RegulatorMSP.member')"
    AnchorPeers:
      - Host: peer.regulator.com
        Port: 7051

  - &Broker
    Name: Broker
    ID: BrokerMSP
    MSPDir: ./crypto-config/peerOrganizations/broker.com/msp
    Policies: &BrokerPolicies
      Readers:
          Type: Signature
          Rule: "OR('BrokerMSP.member')"
      Writers:
          Type: Signature
          Rule: "OR('BrokerMSP.member')"
      Admins:
          Type: Signature
          Rule: "OR('BrokerMSP.member')"
      Endorsement:
          Type: Signature
          Rule: "OR('BrokerMSP.member')"
    AnchorPeers:
      - Host: peer.broker.com
        Port: 7051

  


Orderer: &OrdererDefaults
  OrdererType: solo
  Addresses:
    - orderer.regulator.com:7050
  Policies:
    Readers:
        Type: ImplicitMeta
        Rule: "ANY Readers"
    Writers:
        Type: ImplicitMeta
        Rule: "ANY Writers"
    Admins:
        Type: ImplicitMeta  
        Rule: "ANY Admins"
    BlockValidation:
        Type: ImplicitMeta
        Rule: "ANY Writers"

  BatchTimeout: 2s

  BatchSize:
    MaxMessageCount: 10
    AbsoluteMaxBytes: 98 MB
    PreferredMaxBytes: 512 KB

  Capabilities:
    <<: *OrdererCapabilities

Application: &ApplicationDefaults

  ACLs: &ACLsDefault
    lscc/ChaincodeExists: /Channel/Application/Readers
    lscc/GetDeploymentSpec: /Channel/Application/Readers
    lscc/GetChaincodeData: /Channel/Application/Readers
    lscc/GetInstantiatedChaincodes: /Channel/Application/Readers
    qscc/GetChainInfo: /Channel/Application/Readers
    qscc/GetBlockByNumber: /Channel/Application/Readers
    qscc/GetBlockByHash: /Channel/Application/Readers
    qscc/GetTransactionByID: /Channel/Application/Readers
    qscc/GetBlockByTxID: /Channel/Application/Readers
    cscc/GetConfigBlock: /Channel/Application/Readers
    cscc/GetConfigTree: /Channel/Application/Readers
    cscc/SimulateConfigTreeUpdate: /Channel/Application/Readers
    peer/Propose: /Channel/Application/Writers
    peer/ChaincodeToChaincode: /Channel/Application/Readers
    event/Block: /Channel/Application/Readers
    event/FilteredBlock: /Channel/Application/Readers
    _lifecycle/CheckCommitReadiness: /Channel/Application/Writers
    _lifecycle/CommitChaincodeDefinition: /Channel/Application/Writers
    _lifecycle/QueryChaincodeDefinition: /Channel/Application/Readers
    
  Policies: &ApplicationDefaultPolicies
    Endorsement:
        Type: ImplicitMeta
        Rule: "ANY Endorsement"
    Readers:
        Type: ImplicitMeta
        Rule: "ANY Readers"
    Writers:
        Type: ImplicitMeta
        Rule: "ANY Writers"
    Admins:
        Type: ImplicitMeta
        Rule: "ANY Admins"
    LifecycleEndorsement:
        Type: ImplicitMeta
        Rule: "ANY Endorsement"

  Organizations:
  Capabilities:
    <<: *ApplicationCapabilities
 


Channel: &ChannelDefaults
  Policies:
    Readers:
        Type: ImplicitMeta
        Rule: "ANY Readers"
    Writers:
        Type: ImplicitMeta
        Rule: "ANY Writers"
    Admins:
        Type: ImplicitMeta
        Rule: "ANY Admins"

  Capabilities:
    <<: *ChannelCapabilities

Profiles:
  CompOrdererGenesis:
      <<: *ChannelDefaults
      Orderer:
          <<: *OrdererDefaults
          Organizations:
              - <<: *Orderer
      Consortiums:
        CompConsortium:
            Organizations:
                  - <<: *Regulator
                  - <<: *Broker

      Application:
            <<: *ApplicationDefaults

            Organizations:
                - <<: *Regulator
                - <<: *Broker

  CompChannel:
    <<: *ChannelDefaults
    Consortium: CompConsortium
        
    Application:
      <<: *ApplicationDefaults
        
      Organizations:
        - <<: *Broker
        - <<: *Regulator

crypto-config.yaml 

OrdererOrgs:
  - Name: Orderer
    Domain: regulator.com
    EnableNodeOUs: true
    Specs:
      - Hostname: orderer
      
PeerOrgs:
  - Name: Regulator
    Domain: regulator.com
    EnableNodeOUs: true
    Specs:
      - Hostname: peer.regulator.com
        CommonName: peer.regulator.com
    Users:
      Count: 1

  - Name: Broker
    Domain: broker.com
    EnableNodeOUs: true
    Specs:
      - Hostname: peer.broker.com
        CommonName: peer.broker.com
    Users:
      Count: 1

docker-compose-base.yaml 

version: "2"

networks:
  comp:

volumes:
  data-orderer.regulator.com:
  data-peer.regulator.com:
  data-peer.broker.com:
  couchdb-data-regulator:
    driver: local
  couchdb-data-broker:
    driver: local

services:
  couchdb.regulator.com:
    container_name: couchdb.regulator.com
    image: couchdb:latest
    environment:
      - COUCHDB_USER=<username>
      - COUCHDB_PASSWORD=<password>
    ports:
      - 5984:5984
    volumes:
      - couchdb-data-regulator:/opt/couchdb/data
    networks:
      - comp

  couchdb.broker.com:
    container_name: couchdb.broker.com
    image: couchdb:latest
    environment:
      - COUCHDB_USER=<username>
      - COUCHDB_PASSWORD=<password>
    ports:
      - 6984:5984
    volumes:
      - couchdb-data-broker:/opt/couchdb/data
    networks:
      - comp

  orderer.regulator.com:
    container_name: orderer.regulator.com
    image: hyperledger/fabric-orderer:latest
    command: orderer
    environment:
      - FABRIC_CFG_PATH=/var/hyperledger/config
      - FABRIC_LOGGING_SPEC=DEBUG
    volumes:
      - ${PWD}/config/orderer:/var/hyperledger/config
      - ${PWD}/config/crypto-config/ordererOrganizations/regulator.com/orderers/orderer.regulator.com/msp:/var/hyperledger/msp
      - ${PWD}/config/crypto-config/ordererOrganizations/regulator.com/orderers/orderer.regulator.com/tls:/var/hyperledger/tls
      - data-orderer.regulator.com:/var/ledger
    ports:
      - 7050:7050
    networks:
      - comp

  peer.regulator.com:
    container_name: peer.regulator.com
    image: hyperledger/fabric-peer:latest
    environment:
      - FABRIC_CFG_PATH=/var/hyperledger/config
      - FABRIC_LOGGING_SPEC=DEBUG
      - CORE_VM_DOCKER_HOSTCONFIG_NETWORKMODE=${COMPOSE_PROJECT_NAME}_net
      - CORE_LEDGER_STATE_STATEDATABASE=CouchDB
      - CORE_LEDGER_STATE_COUCHDBCONFIG_COUCHDBADDRESS=couchdb.regulator.com:5984
      - CORE_LEDGER_STATE_COUCHDBCONFIG_USERNAME=<username>
      - CORE_LEDGER_STATE_COUCHDBCONFIG_PASSWORD=<password>
    command: [sh,-c,"sleep 10 && peer node start"]
    volumes:
      - ${PWD}/config/regulator:/var/hyperledger/config
      - ${PWD}/config/crypto-config/peerOrganizations/regulator.com/peers/peer.regulator.com/msp:/var/hyperledger/msp
      - ${PWD}/config/crypto-config/peerOrganizations/regulator.com/peers/peer.regulator.com/tls:/var/hyperledger/tls
      - /var/run/:/var/run/
      - data-peer.regulator.com:/var/hyperledger/production
    depends_on:
      - orderer.regulator.com
      - couchdb.regulator.com
    ports:
      - 7051:7051
      - 7052:7052
    networks:
      - comp
    links:
      - couchdb.regulator.com

  peer.broker.com:
    container_name: peer.broker.com
    image: hyperledger/fabric-peer:latest
    environment:
      - FABRIC_CFG_PATH=/var/hyperledger/config
      - FABRIC_LOGGING_SPEC=DEBUG
      - CORE_VM_DOCKER_HOSTCONFIG_NETWORKMODE=${COMPOSE_PROJECT_NAME}_net
      - CORE_LEDGER_STATE_STATEDATABASE=CouchDB
      - CORE_LEDGER_STATE_COUCHDBCONFIG_COUCHDBADDRESS=couchdb.broker.com:6984
      - CORE_LEDGER_STATE_COUCHDBCONFIG_USERNAME=<username>
      - CORE_LEDGER_STATE_COUCHDBCONFIG_PASSWORD=<password>
    command: [sh,"sleep 10 && peer node start"]
    volumes:
      - ${PWD}/config/regulator:/var/hyperledger/config
      - ${PWD}/config/crypto-config/peerOrganizations/broker.com/peers/peer.broker.com/msp:/var/hyperledger/msp
      - ${PWD}/config/crypto-config/peerOrganizations/broker.com/peers/peer.broker.com/tls:/var/hyperledger/tls
      - /var/run/:/var/run/
      - data-peer.broker.com:/var/hyperledger/production
    depends_on:
      - orderer.regulator.com
      - couchdb.broker.com
    ports:
      - 8051:7051
      - 8052:7052
    networks:
      - comp
    links:
      - couchdb.broker.com
    extra_hosts:
      - "couchdb.broker.com:<machines_ip>" # this one was due to some DNS resolution shenanigans

我希望有人能帮助我解决这个问题，因为我认为我现在正在失去理智。

解决方法

结果证明我刚犯了一个傻瓜。当您查看docker-compose-base.yaml部分下的services > peer.broker.com > volumes文件时，我弄乱了config文件夹路径，因此两个对等端都在相同的配置上运行，但是证书不同，这导致对等端的差异身份验证。

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java.lang.ClassNotFoundException：sun.jdbc.odbc.JdbcOdbcDriver发生异常。为什么？
这是用Java进行XML解析的最佳库
这是用Java进行XML解析的最佳库。
Java的PriorityQueue的内置迭代器不会以任何特定顺序遍历数据结构为什么？
Java的PriorityQueue的内置迭代器不会以任何特定顺序遍历数据结构。为什么？
如何在Java中聆听按键时移动图像
如何在Java中聆听按键时移动图像。
Java“Program to an interface”这是什么意思？
Java“Program to an interface”。这是什么意思？
Java在半透明框架/面板/组件上重新绘画
Java在半透明框架/面板/组件上重新绘画。
Java“ Class.forName”和“ Class.forNamenewInstance”之间有什么区别？
Java“ Class.forName（）”和“ Class.forName（）。newInstance（）”之间有什么区别？
在此环境中不提供编译器也许是在JRE而不是JDK上运行？
在此环境中不提供编译器。也许是在JRE而不是JDK上运行？
Java用相同的方法在一个类中实现两个接口哪种接口方法被覆盖？
Java用相同的方法在一个类中实现两个接口。哪种接口方法被覆盖？
Java 什么是Runtime.getRuntimetotalMemory和freeMemory？
Java 什么是Runtime.getRuntime（）。totalMemory（）和freeMemory（）？
java.library.path中的java.lang.UnsatisfiedLinkError否*****dll
java.library.path中的java.lang.UnsatisfiedLinkError否*****。dll
JavaFX“位置是必需的” 即使在同一包装中
JavaFX“位置是必需的。” 即使在同一包装中
Java 导入两个具有相同名称的类怎么处理？
Java 导入两个具有相同名称的类。怎么处理？
Java 是否应该在HttpServletResponse.getOutputStream/getWriter上调用.close？
Java 是否应该在HttpServletResponse.getOutputStream（）/。getWriter（）上调用.close（）？
Java RegEx元字符和普通点？
Java RegEx元字符（。）和普通点？
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