json转javabean出错

Question

json转换为javaBean出错

javabean如下

package org.twtpush.dto.BrokerStatus;

import org.twtpush.dto.Broker.Connection;

import java.util.List;

/**
 * {
 "id": "default",
 "state": "STARTING",
 "state_since": 1471856089398,
 "version": "1.7.1",
 "home_location": "/opt/apache-apollo-1.7.1",
 "base_location": "/opt/apache-apollo-1.7.1/bin/twt",
 "jvm_metrics": {
 "heap_memory": {
 "used": 75596152,
 "alloc": 218103808,
 "max": 954728448
 },
 "non_heap_memory": {
 "used": 40754176,
 "alloc": 41353216,
 "max": 136314880
 },
 "classes_loaded": 6900,
 "classes_unloaded": 0,
 "threads_current": 36,
 "threads_peak": 41,
 "os_arch": "amd64",
 "os_name": "Linux 4.4.0-34-generic (Ubuntu 16.04.1 LTS)",
 "os_memory_total": 8279302144,
 "os_memory_free": 310333440,
 "os_swap_total": 0,
 "os_swap_free": 15999168512,
 "os_fd_open": 147,
 "os_fd_max": 100000,
 "os_load_average": 0.21,
 "os_cpu_time": 11150000000,
 "os_processors": 8,
 "runtime_name": "11942@nero-Lenovo-Y430P",
 "jvm_name": "Java HotSpot(TM) 64-Bit Server VM 1.7.0_80 (Oracle Corporation)",
 "uptime": 162504,
 "start_time": 1471856086106
 },
 "current_time": 1471856252952,
 "virtual_hosts": [
 "twt"
 ],
 "connectors": [
 "tcp",
 "tls",
 "ws",
 "wss"
 ],
 "connection_counter": 0,
 "connected": 0,
 "connections": [],
 "messages_sent": 0,
 "messages_received": 0,
 "read_counter": 0,
 "write_counter": 0
 }
 * Created by nero on 16-8-22.
 */
public class BrokerStatus {
    private String id;

    private String state;

    private int state_since;

    private String version;

    private String home_location;

    private String base_location;

    private Jvm_metrics jvm_metrics;

    private int current_time;

    private List<String> virtual_hosts ;

    private List<String> connectors ;

    private int connection_counter;

    private int connected;

    private List<Connection> connections ;

    private int messages_sent;

    private int messages_received;

    private int read_counter;

    private int write_counter;

    public BrokerStatus(String id, String state, int state_since, String version, String home_location, String base_location, Jvm_metrics jvm_metrics, int current_time, List<String> virtual_hosts, List<String> connectors, int connection_counter, int connected, List<Connection> connections, int messages_sent, int messages_received, int read_counter, int write_counter) {
        this.id = id;
        this.state = state;
        this.state_since = state_since;
        this.version = version;
        this.home_location = home_location;
        this.base_location = base_location;
        this.jvm_metrics = jvm_metrics;
        this.current_time = current_time;
        this.virtual_hosts = virtual_hosts;
        this.connectors = connectors;
        this.connection_counter = connection_counter;
        this.connected = connected;
        this.connections = connections;
        this.messages_sent = messages_sent;
        this.messages_received = messages_received;
        this.read_counter = read_counter;
        this.write_counter = write_counter;
    }

    public void setId(String id){
        this.id = id;
    }
    public String getId(){
        return this.id;
    }
    public void setState(String state){
        this.state = state;
    }
    public String getState(){
        return this.state;
    }
    public void setState_since(int state_since){
        this.state_since = state_since;
    }
    public int getState_since(){
        return this.state_since;
    }
    public void setVersion(String version){
        this.version = version;
    }
    public String getVersion(){
        return this.version;
    }
    public void setHome_location(String home_location){
        this.home_location = home_location;
    }
    public String getHome_location(){
        return this.home_location;
    }
    public void setBase_location(String base_location){
        this.base_location = base_location;
    }
    public String getBase_location(){
        return this.base_location;
    }
    public void setJvm_metrics(Jvm_metrics jvm_metrics){
        this.jvm_metrics = jvm_metrics;
    }
    public Jvm_metrics getJvm_metrics(){
        return this.jvm_metrics;
    }
    public void setCurrent_time(int current_time){
        this.current_time = current_time;
    }
    public int getCurrent_time(){
        return this.current_time;
    }
    public void setVirtualhosts(List<String> virtual_hosts){
        this.virtual_hosts = virtual_hosts;
    }
    public List<String> getVirtual_hosts(){
        return this.virtual_hosts;
    }
    public void setString(List<String> connectors){
        this.connectors = connectors;
    }
    public List<String> getString(){
        return this.connectors;
    }
    public void setConnection_counter(int connection_counter){
        this.connection_counter = connection_counter;
    }
    public int getConnection_counter(){
        return this.connection_counter;
    }
    public void setConnected(int connected){
        this.connected = connected;
    }
    public int getConnected(){
        return this.connected;
    }
    public void setConnections(List<Connection> connections){
        this.connections = connections;
    }
    public List<Connection> getConnections(){
        return this.connections;
    }
    public void setMessages_sent(int messages_sent){
        this.messages_sent = messages_sent;
    }
    public int getMessages_sent(){
        return this.messages_sent;
    }
    public void setMessages_received(int messages_received){
        this.messages_received = messages_received;
    }
    public int getMessages_received(){
        return this.messages_received;
    }
    public void setRead_counter(int read_counter){
        this.read_counter = read_counter;
    }
    public int getRead_counter(){
        return this.read_counter;
    }
    public void setWrite_counter(int write_counter){
        this.write_counter = write_counter;
    }
    public int getWrite_counter(){
        return this.write_counter;
    }
}

json如下

{"id":"default","state":"STARTING","state_since":1471856089398,"version":"1.7.1","home_location":"/opt/apache-apollo-1.7.1","base_location":"/opt/apache-apollo-1.7.1/bin/twt","jvm_metrics":{"heap_memory":{"used":52671712,"alloc":126877696,"max":954728448},"non_heap_memory":{"used":43066464,"alloc":43581440,"max":136314880},"classes_loaded":6968,"classes_unloaded":0,"threads_current":35,"threads_peak":41,"os_arch":"amd64","os_name":"Linux 4.4.0-34-generic (Ubuntu 16.04.1 LTS)","os_memory_total":8279302144,"os_memory_free":919715840,"os_swap_total":0,"os_swap_free":15999168512,"os_fd_open":140,"os_fd_max":100000,"os_load_average":0.72,"os_cpu_time":238030000000,"os_processors":8,"runtime_name":"11942@nero-Lenovo-Y430P","jvm_name":"Java HotSpot(TM) 64-Bit Server VM 1.7.0_80 (Oracle Corporation)","uptime":64824402,"start_time":1471856086106},"current_time":1471920910619,"virtual_hosts":["twt"],"connectors":["tcp","tls","ws","wss"],"connection_counter":0,"connected":0,"connections":[],"messages_sent":0,"messages_received":0,"read_counter":0,"write_counter":0}

转换带码:

ObjectMapper objectMapper=new ObjectMapper();
BrokerStatus brokerStatus=objectMapper.readValue(EntityUtils.toString(entity), BrokerStatus.class);
                

log:

com.fasterxml.jackson.databind.JsonMappingException: No suitable constructor found for type [simple type, class org.twtpush.dto.BrokerStatus.BrokerStatus]: can not instantiate from JSON object (missing default constructor or creator, or perhaps need to add/enable type information?)
 at [Source: {"id":"default","state":"STARTING","state_since":1471856089398,"version":"1.7.1","home_location":"/opt/apache-apollo-1.7.1","base_location":"/opt/apache-apollo-1.7.1/bin/twt","jvm_metrics":{"heap_memory":{"used":57464656,"alloc":123731968,"max":954728448},"non_heap_memory":{"used":43119848,"alloc":43646976,"max":136314880},"classes_loaded":6969,"classes_unloaded":0,"threads_current":35,"threads_peak":41,"os_arch":"amd64","os_name":"Linux 4.4.0-34-generic (Ubuntu 16.04.1 LTS)","os_memory_total":8279302144,"os_memory_free":609484800,"os_swap_total":0,"os_swap_free":15999168512,"os_fd_open":140,"os_fd_max":100000,"os_load_average":0.63,"os_cpu_time":241880000000,"os_processors":8,"runtime_name":"11942@nero-Lenovo-Y430P","jvm_name":"Java HotSpot(TM) 64-Bit Server VM 1.7.0_80 (Oracle Corporation)","uptime":65720718,"start_time":1471856086106},"current_time":1471921806830,"virtual_hosts":["twt"],"connectors":["tcp","tls","ws","wss"],"connection_counter":0,"connected":0,"connections":[],"messages_sent":0,"messages_received":0,"read_counter":0,"write_counter":0}; line: 1, column: 2]
    at 

com.fasterxml.jackson.databind.JsonMappingException.from(JsonMappingException.java:148)
at com.fasterxml.jackson.databind.deser.BeanDeserializerBase.deserializeFromObjectUsingNonDefault(BeanDeserializerBase.java:1080)
at com.fasterxml.jackson.databind.deser.BeanDeserializer.deserializeFromObject(BeanDeserializer.java:295)
at com.fasterxml.jackson.databind.deser.BeanDeserializer.deserialize(BeanDeserializer.java:142)
at com.fasterxml.jackson.databind.ObjectMapper._readMapAndClose(ObjectMapper.java:3564)
at com.fasterxml.jackson.databind.ObjectMapper.readValue(ObjectMapper.java:2580)
at org.twtpush.service.impl.BrokerServiceImpl.getBrokerStatus(BrokerServiceImpl.java:76)
at org.twtpush.service.IBrokerServiceTest.getBrokerStatus(IBrokerServiceTest.java:26)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:47)
at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)
at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:44)
at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17)
at org.springframework.test.context.junit4.statements.RunBeforeTestMethodCallbacks.evaluate(RunBeforeTestMethodCallbacks.java:73)
at org.springframework.test.context.junit4.statements.RunAfterTestMethodCallbacks.evaluate(RunAfterTestMethodCallbacks.java:82)
at org.springframework.test.context.junit4.statements.SpringRepeat.evaluate(SpringRepeat.java:73)
at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:271)
at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.runChild(SpringJUnit4ClassRunner.java:224)
at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.runChild(SpringJUnit4ClassRunner.java:83)
at org.junit.runners.ParentRunner$3.run(ParentRunner.java:238)
at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:63)
at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:236)
at org.junit.runners.ParentRunner.access$000(ParentRunner.java:53)
at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:229)
at org.springframework.test.context.junit4.statements.RunBeforeTestClassCallbacks.evaluate(RunBeforeTestClassCallbacks.java:61)
at org.springframework.test.context.junit4.statements.RunAfterTestClassCallbacks.evaluate(RunAfterTestClassCallbacks.java:68)
at org.junit.runners.ParentRunner.run(ParentRunner.java:309)

Answer 1

你的BrokenStatus类没有默认的构造函数，需要加一个

public BrokenStatus() {
}

另外你好几个字段的整型超范围了，得改成Long

Answer 2

你需要的是一个无參的构造器，例如：

public class BrokerStatus {
    private String id;

    private String state;

    private int state_since;

    private String version;

    private String home_location;

    private String base_location;

    private Jvm_metrics jvm_metrics;

    private int current_time;

    private List<String> virtual_hosts ;

    private List<String> connectors ;

    private int connection_counter;

    private int connected;

    private List<Connection> connections ;

    private int messages_sent;

    private int messages_received;

    private int read_counter;

    private int write_counter;
    
    public BrokerStatus() {
    }

    public BrokerStatus(String id, String state, int state_since, String version, String home_location, String base_location, Jvm_metrics jvm_metrics, int current_time, List<String> virtual_hosts, List<String> connectors, int connection_counter, int connected, List<Connection> connections, int messages_sent, int messages_received, int read_counter, int write_counter) {
        this.id = id;
        this.state = state;
        this.state_since = state_since;
        this.version = version;
        this.home_location = home_location;
        this.base_location = base_location;
        this.jvm_metrics = jvm_metrics;
        this.current_time = current_time;
        this.virtual_hosts = virtual_hosts;
        this.connectors = connectors;
        this.connection_counter = connection_counter;
        this.connected = connected;
        this.connections = connections;
        this.messages_sent = messages_sent;
        this.messages_received = messages_received;
        this.read_counter = read_counter;
        this.write_counter = write_counter;
    }

    ...
    ...
}

要么你就配合@JsonCreator，修改你那个已经写好的有參构造器