writeValueAsString封装成工具类

封装成工具类

<span style="font-family:Microsoft YaHei;">public static String toJsonByObject(Object obj){
        String jsonStr = null;
        try {
            jsonStr =  mapper.writeValueAsString(obj);
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        return jsonStr;
    }
    </span>

public static String toJsonByObject(Object obj){
		String jsonStr = null;
		try {
			jsonStr =  mapper.writeValueAsString(obj);
		} catch (IOException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
		return jsonStr;
	}
	

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如何把Java对象转化成json字符串并打印出来呢？

这里就用到了jackon的jar包，使用writeValuesAsString的方法就可以把对角转化成json字符串。

下面通过一个demo，来仔细体会下如何去转化！

1：先建一个javaBean。

package com.sino.objectmapperdemo;

public class BaseObject {
    private String userName;
    private String userCode;
    private double weight;
    private int height;
    private boolean sex;
    private String[] array;
    private BaseObject innerBaseObject;

    public String getUserName() {
        return userName;
    }
    public void setUserName(String userName) {
        this.userName = userName;
    }
    public String getUserCode() {
        return userCode;
    }
    public void setUserCode(String userCode) {
        this.userCode = userCode;
    }
    public double getWeight() {
        return weight;
    }
    public void setWeight(double weight) {
        this.weight = weight;
    }
    public int getHeight() {
        return height;
    }
    public void setHeight(int height) {
        this.height = height;
    }
    public boolean isSex() {
        return sex;
    }
    public void setSex(boolean sex) {
        this.sex = sex;
    }
    public String[] getArray() {
        return array;
    }
    public void setArray(String[] array) {
        this.array = array;
    }
    public BaseObject getInnerBaseObject(){
        return innerBaseObject;
    }
    public void setInnerBaseObject(BaseObject innerBaseObject){
        this.innerBaseObject = innerBaseObject;
    }


}

2:在MainActivity中，对其进行赋值和转化操作，并打印出来。

package com.sino.objectmapperdemo;

import java.io.IOException;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.Map;

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

import android.os.Bundle;
import android.app.Activity;
import android.view.Menu;
/**
 * 使用jackon的ObjectMapper的writeValueAsString方法可以把java对象转化成json字符串
 * 输出的结果是：{"array":["80","90","95"],"height":170,"innerBaseObject":{"array":["65","68","75"],
 * "height":171,"innerBaseObject":null,"userCode":"2号","userName":"李四","weight":75.5,"sex":true},
 * "userCode":"1号","userName":"张三","weight":65.5,"sex":true}
 *
 */
public class MainActivity extends Activity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
    try {
        ObjectMapper objectMapper = new ObjectMapper();
//      ArrayList list = new ArrayList();
//      Map<String,Object> map = new HashMap<String,Object>();
        BaseObject object1 = new BaseObject();
        object1.setUserName("张三");
        object1.setUserCode("1号");
        object1.setWeight(65.5);
        object1.setHeight(170);
        object1.setSex(true);
        String[] score={"80","90","95"};
        object1.setArray(score);

        BaseObject object2=new BaseObject();
        object2.setUserName("李四");
        object2.setUserCode("2号");
        object2.setWeight(75.5);
        object2.setHeight(171);
        object2.setSex(true);
        score=new String[3];
        score[0]="65";
        score[1]="68";
        score[2]="75";
        object2.setArray(score);
//        object2成为object1的内部类
        object1.setInnerBaseObject(object2);
//        list.add(object1);
//        map.put("baseObject", list);
//        把对象转化成json字符串
        String json = objectMapper.writeValueAsString(object1);
        System.out.println(json);
        } catch (JsonGenerationException e) {
            e.printStackTrace();
        } catch (JsonMappingException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }


    }


}