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转换JSON工具——Jackson的简单使用

  什么是Jackson

    可以轻松实现Java对象与JSON字符串的转换

  准备工作:导包

    Jackson的jar all下载地址:http://jackson.codehaus.org/1.7.6/jackson-all-1.7.6.jar

  1.实体对象转JSON  

    jackson使用getter方法定位属性(而不是字段)
     可以通过添加注解 @JsonIgnore 使某些getter来进行忽略

  将对象或集合转为json字符串

package cn.jackson;

import java.io.IOException;
import java.util.Arrays;
import java.util.List;

import org.codehaus.jackson.JsonGenerationException;
import org.codehaus.jackson.annotate.JsonIgnore;
import org.codehaus.jackson.map.JsonMappingException;
import org.codehaus.jackson.map.ObjectMapper;

public class Customer {

    private String name;
    private String id;
    
    public Customer() {
        super();
    }
    public Customer(String name, String id) {
        super();
        this.name = name;
        this.id = id;
    }
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }
    public String getId() {
        return id;
    }
    public void setId(String id) {
        this.id = id;
    }
    @JsonIgnore
    public String getCity(){
        return "北京";
    }
    public String getBirth(){
        return "1988";
    }
    
    public static void main(String[] args) throws JsonGenerationException, JsonMappingException, IOException {
        //导包
        //创建ObjectMapper对象
        ObjectMapper mapper = new ObjectMapper();
        //
        Customer cust = new Customer("jackson", "1001");
        String jsonStr = mapper.writeValueAsString(cust);
        System.out.println(jsonStr);
        
        List<Customer> list = (List) Arrays.asList(cust,new Customer("33","离魂计"));
        String jsonStrList = mapper.writeValueAsString(list);
        System.out.println(jsonStrList);
        /**
         * jackson使用getter方法定位属性
         * 可以通过添加注解 @JsonIgnore 使某些getter来进行忽略
         */
    }
}

  结果:

{"name":"jackson","id":"1001","birth":"1988"}
[{"name":"jackson","id":"1001","birth":"1988"},{"name":"33","id":"离魂计","birth":"1988"}]

  于是ajax_day02可以转为使用Jackson简化:

    ObjectMapper mapper=new ObjectMapper();
        String result=mapper.writeValueAsString(sc);

 

  2.JSON字符串转对象

ObjectMapper mapper = new ObjectMapper();
        String json = "{\"name\":\"jackson\",\"id\":\"1001\"}";
        Customer c = mapper.readValue(json, Customer.class);
        System.out.println(c.getId());

 

  //注意"的转义操作

 

转换JSON工具——Jackson的简单使用