Java获取Google天气预报

package cn.edu.ytu.server;

/**
 * 一个利用Java获取Google天气预报的例子
 */
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.GridLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.KeyAdapter;
import java.awt.event.KeyEvent;
import java.io.*;
import java.net.MalformedURLException;
import java.net.URL;

import org.w3c.dom.*;

import javax.swing.BorderFactory;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.JTextArea;
import javax.swing.JTextField;
import javax.xml.parsers.*;

public class GoogleReport extends JFrame implements ActionListener {
    JPanel p1 = new JPanel();
    JTextField tf = new JTextField(2);

    JButton but = new JButton("查询");
    JPanel p2 = new JPanel();
    JTextArea ta = new JTextArea(10, 40);

    public GoogleReport() {
        super("天气预报查询");
        // 设置p1面板

        p1.setLayout(new BorderLayout());
        tf.addKeyListener(new TfListener());// 设置tf监听器

        tf.setBorder(BorderFactory.createLineBorder(Color.blue, 1));
        
        p1.add(tf, BorderLayout.CENTER);
        but.setBorder(BorderFactory.createLineBorder(Color.green));// 设置按钮边框颜色

        // 增加but事件监听器

        but.addActionListener(this);
        p1.add(but, BorderLayout.EAST);
        add(p1, BorderLayout.NORTH);
        // 设置p2面板

        p2.setLayout(new GridLayout(1, 1));

        JScrollPane sp = new JScrollPane(ta);
        ta.setEnabled(false);
        ta.setBorder(BorderFactory.createLineBorder(Color.red, 2));
        p2.add(sp);
        add(p2, BorderLayout.CENTER);

        this.setSize(500, 400);
        this.setLocationRelativeTo(null);
        this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        this.setVisible(true);
    }

    public static void main(String[] args) {
        new GoogleReport();
    }

    /**
     * getWeather->由city值获得天气情况
     *
     * @param city
     * @return 获得的天气情况的字符串
     */
    public String getWeather(String city) {

        try {
            URL ur = new URL(""
                    + city);
            InputStream instr = ur.openStream();
            String s;
            String str;
            BufferedReader in = new BufferedReader(new InputStreamReader(instr));
            StringBuffer sb = new StringBuffer();

            Writer out = new BufferedWriter(new OutputStreamWriter(
                    new FileOutputStream("weather.txt"), "utf-8"));
            while ((s = in.readLine()) != null) {
                sb.append(s);
            }
            str = new String(sb);
            out.write(str);
            out.close();
            in.close();

        } catch (MalformedURLException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
        File f = new File("weather.txt");
        DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
        String str = null;
        try {
            DocumentBuilder builder = factory.newDocumentBuilder();
            Document doc = builder.parse(f);
            NodeList nl = (NodeList) doc
                    .getElementsByTagName("forecast_conditions");// 获得XML文档的forecast_conditions元素

            NodeList n2 = nl.item(0).getChildNodes();// 获得第一个forecast_condition的全部子节点


            str = "今天是"
                    + n2.item(0).getAttributes().item(0).getNodeValue()
                    + ","
                    + n2.item(4).getAttributes().item(0).getNodeValue()
                    + ","// 获得n2的第五个元素current_conditions

                    + "最低气温"
                    + n2.item(1).getAttributes().item(0).getNodeValue()
                    + "℃,"// 获得n2的第二个元素low

                    + "最高气温"
                    + n2.item(2).getAttributes().item(0).getNodeValue() + "℃";// 获得n2的第二个元素hight

        } catch (Exception e) {
        }
        return str;
    }

    private class TfListener extends KeyAdapter {
        public void keyPressed(KeyEvent e) {
            if (e.getKeyCode() == KeyEvent.VK_ENTER) {
                String s = tf.getText();
                tf.setText("");
                String ss = getWeather(s);
                // ta.setBorder(BorderFactory.createLineBorder(Color.RED,1));

                ta.append(ss + "\n");
            }
        }
    }

    @Override
    public void actionPerformed(ActionEvent e) {
        if (e.getSource() == but) {
            String s = tf.getText();
            tf.setText("");
            String ss = getWeather(s);
            ta.append(ss + "\n");
        }
    }

}