net.sf.json.JSONException: A JSONArray text must start with ‘[‘ at character

喜欢ヅ旅行 2022-03-02 03:10 562阅读 0赞

### **错误背景** ###

后端返回json数据给前端页面报错

--------------------

### **错误代码** ###

package cn.com.service;
    import java.io.*;
    import javax.servlet.http.HttpServletResponse;
    import net.*;
    import org.*;
    import cn.com.bean.User;
    @Repository(value="regedit")
    @Scope("prototype")
    public class Regedit implements ModelDriven<User>{
    @Autowired
    private SessionFactory sf;
    @Autowired
    private User user;
    @Transactional
    public String regedit_user(){
    	//获取session对象
    	String toast="用户名已存在，请重新输入";	
    	 HttpServletResponse response = ServletActionContext.getResponse();
    	//设置response输出json便于调试
    	 response.setCharacterEncoding("utf-8");
    	 PrintWriter out;
    	try {
    		out = response.getWriter();
    		 JSONArray json=JSONArray.fromObject(toast);
    	     out.write(json.toString());
    	     out.flush();
    	     out.close();
    	} catch (IOException e) {
    		// TODO Auto-generated catch block
    		e.printStackTrace();
    	}
    	
    	return "success";
    }
    public User getModel() {
    
    	return user;
    }
    }

--------------------

### 报错的原因 ###

**把一个object类型的变成json数组的形式，必须要有\[\]这个标志存在**

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzM3NTkxNjM3_size_16_color_FFFFFF_t_70][]

### **解决方案** ###

**1、在字符串里面添加\[\]进去**![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzM3NTkxNjM3_size_16_color_FFFFFF_t_70 1][]

**2、用JSONObject**

JSONArray json=JSONArray.fromObject(toast);  
         out.write(json.toString());

把改成

JSONObject json=new JSONObject();  
         json.put("tom", toast);

[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzM3NTkxNjM3_size_16_color_FFFFFF_t_70]: /images/20220302/496c1090a19a40dcbf093bd469c9a9f7.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzM3NTkxNjM3_size_16_color_FFFFFF_t_70 1]: /images/20220302/2a6d98c4e1fc40489bf469ad0511254e.png