从HTTP request的body中拿到JSON并反序列化为一个对象

import com.google.gson.Gson;
import org.apache.struts2.ServletActionContext;

import javax.servlet.ServletRequest;
import java.io.*;

/**
 * Created by sky.tian on 2015/1/12.
 */
public class Test {

    private static final int DEFAULT_BUFFER_SIZE = 1024 * 4;

    private static final Gson gson = new Gson();

    public <T> T parseRequestBody(Class<T> type) throws IOException {
        ServletRequest request = ServletActionContext.getRequest();
        InputStream inputStream = request.getInputStream();
        String json = getRequestBodyJson(inputStream);
        return gson.fromJson(json, type);
    }

    /**
     * 得到HTTP请求body中的JSON字符串
     * @param inputStream
     * @return
     * @throws IOException
     */
    private String getRequestBodyJson(InputStream inputStream) throws IOException {
        Reader input = new InputStreamReader(inputStream);
        Writer output = new StringWriter();
        char[] buffer = new char[DEFAULT_BUFFER_SIZE];
        int n = 0;
        while(-1 != (n = input.read(buffer))) {
            output.write(buffer, 0, n);
        }
       return output.toString();
    }

}