Question

我遇到HttpConnection向我的服务器发布数据有困难。一切顺利的第一次。第二次说; “流已经打开”，但我在回复后关闭了所有内容。

这是我的代码：

import javax.microedition.io.Connector;
import javax.microedition.io.HttpConnection;
import javax.microedition.location.*;
import java.io.*;

class GetSnowheights
{    
    HttpConnection http = null;
    QualifiedCoordinates q = null;
    public String result = "Geen data";
    private boolean running;

    public GetSnowheights(QualifiedCoordinates q) {        
        try
        {
            /*
            this.http = (HttpConnection)Connector.open("http://www.diamond4it.nl/bb/");                
            this.http.setRequestMethod(HttpConnection.POST);
            this.http.setRequestProperty("Content-Type", "application/x-www-form-urlencoded");
            */
            //Internet.getInstance();
            this.http = Internet.getConnection();
        }catch(Exception err){
           err.printStackTrace();
        }
        this.q = q;
        this.result = "Running";
    }

    public void GetResult(){
        StringBuffer sb = new StringBuffer();        
        this.result = "GetResult";

        if(this.http != null){

            OutputStream os = null;
            InputStream is = null;
            try
            {
                //Send request
                os = this.http.openOutputStream();
                String data = "lat=1&lng=1";
                //String data = "lat=" + this.q.getLatitude() + "&lng=" + this.q.getLongitude();
                os.write(data.getBytes());
                os.flush();
                os.close();
                this.result = "dataSend";                

                //Check response and read data
                int res = this.http.getResponseCode();
                this.result = "Result: " + res;
                if(res == 200){
                    is = this.http.openInputStream();
                    int ch;
                    // Check the Content-Length first 
                    long len = this.http.getLength();
                    if(len!=-1) { 
                        for(int i = 0;i<len;i++){
                            if((ch = is.read())!= -1){
                                sb.append((char)ch);
                            }
                        }
                    } else { 
                        // if the content-length is not available 
                        while ((ch = is.read()) != -1){
                            sb.append((char)ch); 
                        }
                    }
                    is.close();
                }

                this.result = sb.toString();

            }catch(Exception err){
                //err.printStackTrace();
                this.result = err.toString() + "\r\n" + err.getMessage();
            }finally{
                if(is != null){
                    try{
                        is.close();
                    }catch(Exception err){
                        err.printStackTrace();
                    }
                }
                if(os != null){
                    try{
                        //os.flush();
                        os.close();
                    }catch(Exception err){
                        err.printStackTrace();
                    }
                }

                /*
                if(http != null){
                    try{
                        http.close();
                    }catch(Exception err){
                        err.printStackTrace();
                    }
                }
                */
            }

        }else{
            this.result = "No connection";
        }
    }    

}

Answer 1

2个想法：

为什么你在http.close()块中注释了finally？我们应该总是关闭HttpConnections。
你不是要同时从多个线程中调用GetResult()吗？如果是，则通过在其定义中添加synchronized关键字来使方法同步。

P.S。我觉得这个课程的设计有点误导。错误地使用它会很容易犯错误。我将GetSnowheights和GetResult合并到唯一的同步方法中。

j2me openOutputStream流已经打开

1 个答案: