jsonConfig处理日期及对象级联问题

      项目中经常用到ajax请求后台，返回给前台json对象字符串。有些实体包含字段可能有日期、list、以及级联对象情况。因此，我们需要有针对性处理，

例如日期date类型，我们要给它转为我们所想要的格式的日期字符串，返回给前台。list我们要去除掉，级联对象，只提取我们所需要的字段值。

例如实体product：

/**
 * 
 */
package com.hik.entity;

import java.util.ArrayList;
import java.util.Date;
import java.util.List;

import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.persistence.JoinColumn;
import javax.persistence.ManyToOne;
import javax.persistence.OneToMany;
import javax.persistence.Table;

import org.hibernate.annotations.GenericGenerator;

/**
 * @ClassName: Product
 * @Description: TODO
 * @author jed
 * @date 2017年2月26日下午7:08:59
 *
 */
@Entity
@Table(name="t_product")
public class Product {
    
    private int id;
    private String name; //名字
    private int price; //价格
    private int stock; //存储
    private String proPic; //图片
    private String description; //描述
    private int hot; //默认0不热卖  0:不热卖 ,1：热卖
    private Date hotTime; //热卖时间
    private int specialPrice;  //特价0不打特价  0:不打热价,1：打特价
    private Date specialPriceTime; //特价时间
    
    private ProductBigType bigType; //商品和商品大类是多对一关系
    private ProductSmallType smallType; //商品和商品小类是多对一关系
    private List<OrderProduct> orderProductList = new ArrayList<OrderProduct>(); //商品和订单商品是一对多关系
    
    @Id
    @GeneratedValue(generator="_native")
    @GenericGenerator(name="_native",strategy="native")
    public int getId() {
        return id;
    }
    public void setId(int id) {
        this.id = id;
    }
    
    @Column(length=50)
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }
    public int getPrice() {
        return price;
    }
    public void setPrice(int price) {
        this.price = price;
    }
    public int getStock() {
        return stock;
    }
    public void setStock(int stock) {
        this.stock = stock;
    }
    public String getProPic() {
        return proPic;
    }
    public void setProPic(String proPic) {
        this.proPic = proPic;
    }
    @Column(length=2000)
    public String getDescription() {
        return description;
    }
    public void setDescription(String description) {
        this.description = description;
    }
    public int getHot() {
        return hot;
    }
    public void setHot(int hot) {
        this.hot = hot;
    }
    public Date getHotTime() {
        return hotTime;
    }
    public void setHotTime(Date hotTime) {
        this.hotTime = hotTime;
    }
    public int getSpecialPrice() {
        return specialPrice;
    }
    public void setSpecialPrice(int specialPrice) {
        this.specialPrice = specialPrice;
    }
    public Date getSpecialPriceTime() {
        return specialPriceTime;
    }
    public void setSpecialPriceTime(Date specialPriceTime) {
        this.specialPriceTime = specialPriceTime;
    }
    
    @ManyToOne
    @JoinColumn(name="bigTypeId") //外键关联
    public ProductBigType getBigType() {
        return bigType;
    }
    public void setBigType(ProductBigType bigType) {
        this.bigType = bigType;
    }
    
    @ManyToOne
    @JoinColumn(name="smallTypeId") //外键关联
    public ProductSmallType getSmallType() {
        return smallType;
    }
    public void setSmallType(ProductSmallType smallType) {
        this.smallType = smallType;
    }
    
    @OneToMany
    @JoinColumn(name="productId")
    public List<OrderProduct> getOrderProductList() {
        return orderProductList;
    }
    public void setOrderProductList(List<OrderProduct> orderProductList) {
        this.orderProductList = orderProductList;
    }
    
    

}

实体对象有Date类型字段，有list，还有级联对象ProductBigType、ProductSmallType。

处理使用到jsonConfig，其中jsonConfig.setExcludes 方法去除不需要的属性，前台不展示。registerJsonValueProcessor 处理得到我们想要的字段值

/**
     * 
     * @MethodName: list
     * @Description: 获取商品
     * @author jed
     * @date 2017年5月7日下午5:23:23
     * @param @return    
     * @return String    返回类型
     * @return
     * @throws Exception 
     *
     */
    public String list() throws Exception{
        PageBean pageBean = new PageBean(Integer.parseInt(page), Integer.parseInt(rows));
        List<Product> productList = productService.findProductList(productDetail, pageBean);
        long total = productService.getProductCount(productDetail);
        JsonConfig jsonConfig = new JsonConfig();
        jsonConfig.setExcludes(new String[]{"orderProductList"}); //去除要排除的属性   前台不展示
        jsonConfig.registerJsonValueProcessor(java.util.Date.class, new DateJsonValueProcessor("yyyy-MM-dd")); //日期处理
        jsonConfig.registerJsonValueProcessor(ProductBigType.class, new ObjectJsonValueProcessor(new String[]{"id","name"}, ProductBigType.class));//商品大类的id和name
        jsonConfig.registerJsonValueProcessor(ProductSmallType.class, new ObjectJsonValueProcessor(new String[]{"id","name"},ProductSmallType.class )); //商品小类的id和name
        JSONArray rows = JSONArray.fromObject(productList, jsonConfig);
        JSONObject result = new JSONObject();
        result.put("rows", rows);
        result.put("total", total);
        ResponseUtil.write(ServletActionContext.getResponse(), result);
        return null;
    }

日期处理类：实现JsonValueProcessor

package com.hik.action;

import java.text.SimpleDateFormat;

import net.sf.json.JsonConfig;
import net.sf.json.processors.JsonValueProcessor;

/**
 * json-lib 日期处理类
 * @author Administrator
 *
 */
public class DateJsonValueProcessor implements JsonValueProcessor{

    private String format;  
    
    public DateJsonValueProcessor(String format){  
        this.format = format;  
    }  
    
    public Object processArrayValue(Object value, JsonConfig jsonConfig) {
        // TODO Auto-generated method stub
        return null;
    }

    public Object processObjectValue(String key, Object value, JsonConfig jsonConfig) {
        if(value == null)  
        {  
            return "";  
        }  
        if(value instanceof java.sql.Timestamp)  
        {  
            String str = new SimpleDateFormat(format).format((java.sql.Timestamp)value);  
            return str;  
        }  
        if (value instanceof java.util.Date)  
        {  
            String str = new SimpleDateFormat(format).format((java.util.Date) value);  
            return str;  
        }  
          
        return value.toString(); 
    }

}

对象级联处理：实现JsonValueProcessor

package com.hik.action;

import java.beans.PropertyDescriptor;
import java.lang.reflect.Method;

import net.sf.json.JSONObject;
import net.sf.json.JsonConfig;
import net.sf.json.processors.JsonValueProcessor;

/**
 * 解决对象级联问题
 * @author Administrator
 *
 */
public class ObjectJsonValueProcessor implements JsonValueProcessor{

    /**
     * 保留的字段
     */
    private String[] properties;  
    
    /**
     * 处理类型
     */
    private Class<?> clazz;  
    
    /**
     * 构造方法 
     * @param properties
     * @param clazz
     */
    public ObjectJsonValueProcessor(String[] properties,Class<?> clazz){  
        this.properties = properties;  
        this.clazz =clazz;  
    }  
    
    public Object processArrayValue(Object arg0, JsonConfig arg1) {
        // TODO Auto-generated method stub
        return null;
    }

    public Object processObjectValue(String key, Object value, JsonConfig jsonConfig) {
        PropertyDescriptor pd = null;  
        Method method = null;  
        StringBuffer json = new StringBuffer("{");  
        try{  
            for(int i=0;i<properties.length;i++){  
                pd = new PropertyDescriptor(properties[i], clazz);  
                method = pd.getReadMethod();  
                String v = String.valueOf(method.invoke(value));  
                json.append("'"+properties[i]+"':'"+v+"'");  
                json.append(i != properties.length-1?",":"");  
            }  
            json.append("}");  
        }catch (Exception e) {  
            e.printStackTrace();  
        }  
        return JSONObject.fromObject(json.toString());  
    }

}