JsonRender.java

/**
 * Copyright (c) 2011-2013, James Zhan 詹波 (jfinal@126.com).
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package net.tooan.ynpay.third.jfinal.render;

import com.google.gson.Gson;
import com.google.gson.GsonBuilder;
import net.tooan.ynpay.third.jfinal.kit.JsonKit;

import java.io.IOException;
import java.io.PrintWriter;
import java.util.Enumeration;
import java.util.HashMap;
import java.util.Map;

/**
 * JsonRender.
 * <p/>
 * IE 不支持content type 为 application/json, 在 ajax 上传文件完成后返回 json时 IE 提示下载文件,<br>
 * 解决办法是使用： render(new JsonRender(params).forIE());
 */
public class JsonRender extends Render {

    private static final long serialVersionUID = 3606364198859021837L;

    /**
     * http://zh.wikipedia.org/zh/MIME
     * 在wiki中查到: 尚未被接受为正式数据类型的subtype，可以使用x-开始的独立名称（例如application/x-gzip）
     * 所以以下可能要改成 application/x-json
     * <p/>
     * 通过使用firefox测试,struts2-json-plugin返回的是 application/json, 所以暂不改为 application/x-json
     * 1: 官方的 MIME type为application/json, 见 http://en.wikipedia.org/wiki/MIME_type
     * 2: IE 不支持 application/json, 在 ajax 上传文件完成后返回 json时 IE 提示下载文件
     */
    private static final String contentType = "application/json;charset=" + getEncoding();
    private static final String contentTypeForIE = "text/html;charset=" + getEncoding();
    private boolean forIE = false;
    private static int convertDepth = 8;

    private static final Gson gson = new GsonBuilder().setDateFormat("yyyy-MM-dd HH:mm:ss").create();

    public JsonRender forIE() {
        forIE = true;
        return this;
    }

    private String jsonText;
    private String[] attrs;

    public JsonRender() {

    }

    @SuppressWarnings("serial")
    public JsonRender(final String key, final Object value) {
        if (key == null)
            throw new IllegalArgumentException("The parameter key can not be null.");
        this.jsonText = JsonKit.mapToJson(new HashMap<String, Object>() {{
            put(key, value);
        }}, convertDepth);
    }

    public JsonRender(String[] attrs) {
        if (attrs == null)
            throw new IllegalArgumentException("The parameter attrs can not be null.");
        this.attrs = attrs;
    }

    public JsonRender(String jsonText) {
        if (jsonText == null)
            throw new IllegalArgumentException("The parameter jsonString can not be null.");
        this.jsonText = jsonText;
    }

    public JsonRender(Object object) {
        if (object == null)
            throw new IllegalArgumentException("The parameter object can not be null.");
        this.jsonText = gson.toJson(object);
    }

    public static void setConvertDepth(int convertDepth) {
        if (convertDepth < 2)
            throw new IllegalArgumentException("convert depth can not less than 2.");
        JsonRender.convertDepth = convertDepth;
    }

    public void render() {
        if (jsonText == null)
            buildJsonText();

        PrintWriter writer = null;
        try {
            response.setHeader("Pragma", "no-cache");    // HTTP/1.0 caches might not implement Cache-Control and might only implement Pragma: no-cache
            response.setHeader("Cache-Control", "no-cache");
            response.setDateHeader("Expires", 0);

            response.setContentType(forIE ? contentTypeForIE : contentType);
            writer = response.getWriter();
            writer.write(jsonText);
            writer.flush();
        } catch (IOException e) {
            throw new RenderException(e);
        } finally {
            if (writer != null)
                writer.close();
        }
    }

    @SuppressWarnings({"rawtypes", "unchecked"})
    private void buildJsonText() {
        Map map = new HashMap();
        if (attrs != null) {
            for (String key : attrs)
                map.put(key, request.getAttribute(key));
        } else {
            Enumeration<String> attrs = request.getAttributeNames();
            while (attrs.hasMoreElements()) {
                String key = attrs.nextElement();
                Object value = request.getAttribute(key);
                map.put(key, value);
            }
        }

        this.jsonText = JsonKit.mapToJson(map, convertDepth);
    }
}