JsonErrorRender.java

package cn.dreampie.common.web.render;

import cn.dreampie.common.utils.ValidateUtils;
import com.jfinal.render.Render;
import com.jfinal.render.RenderException;

import java.io.IOException;
import java.io.PrintWriter;

/**
 * Created by wangrenhui on 14-4-28.
 */
public class JsonErrorRender extends Render {

    private static final long serialVersionUID = -7175292712918557096L;
    private static final String contentType = "application/json;charset=" + getEncoding();
    private static final String contentTypeForIE = "text/html;charset=" + getEncoding();

    protected static final String json404 = "404 Not Found";
    protected static final String json500 = "500 Internal Server Error";

    protected static final String json401 = "401 Unauthorized";
    protected static final String json403 = "403 Forbidden";

    protected int errorCode;
    private boolean forIE = false;

    public JsonErrorRender(int errorCode, String view) {
        this.errorCode = errorCode;
        this.view = view;
    }

    public void render() {
        String header = request.getHeader("USER-AGENT").toLowerCase();
        forIE = header.indexOf("msie") > 0 ? true : false;

        response.setStatus(getErrorCode());  // HttpServletResponse.SC_XXX_XXX

        // render with json
        String errorJson = null;
        Object error = request.getAttribute("errorJson");
        if (ValidateUtils.me().isNullOrEmpty(error)) {
            errorJson = getErrorJson();
        } else {
            errorJson = error.toString();
        }

        // render with html content
        PrintWriter writer = null;
        try {
            response.setContentType(forIE ? contentTypeForIE : contentType);
            writer = response.getWriter();
            writer.write(errorJson);
            writer.flush();
        } catch (IOException e) {
            throw new RenderException(e);
        } finally {
            if (writer != null)
                writer.close();
        }
    }

    public String getErrorJson() {
        int errorCode = getErrorCode();
        if (errorCode == 404)
            return json404;
        if (errorCode == 500)
            return json500;
        if (errorCode == 401)
            return json401;
        if (errorCode == 403)
            return json403;
        return errorCode + " Error";
    }

    public int getErrorCode() {
        return errorCode;
    }
}