Java根据Url下载图片

package com.ronniewang.downloadpicture;

import java.io.DataInputStream;
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.net.MalformedURLException;
import java.net.URL;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.ArrayList;

import com.mysql.jdbc.Connection;
import com.mysql.jdbc.Statement;
import com.ronniewang.utilities.JdbcUtil;

public class DownloadPicture {

public static void main(String[] args) {
DownloadPicture downloadPicture = new DownloadPicture();
ArrayList<String> urlList = downloadPicture.readUrlList();
downloadPicture.downloadPicture(urlList);
}

/**
* 传入要下载的图片的url列表，将url所对应的图片下载到本地
* @param urlList
*/
private void downloadPicture(ArrayList<String> urlList) {
URL url = null;
int imageNumber = 0;

for (String urlString : urlList) {
try {
url = new URL(urlString);
DataInputStream dataInputStream = new DataInputStream(url.openStream());
String imageName = imageNumber + ".jpg";
FileOutputStream fileOutputStream = new FileOutputStream(new File(imageName));

byte[] buffer = new byte[1024];
int length;

while ((length = dataInputStream.read(buffer)) > 0) {
fileOutputStream.write(buffer, 0, length);
}

dataInputStream.close();
fileOutputStream.close();
imageNumber++;
} catch (MalformedURLException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
}
}

/**
* 连接mysql数据库，通过查询数据库读取要下载的图片的url列表
* @return
*/
private ArrayList<String> readUrlList() {
ArrayList<String> urlList = new ArrayList<String>();
try {
Connection connection = (Connection) JdbcUtil.getConnection();
Statement statement = (Statement) connection.createStatement();
String sql = "select url from url"; //查询语句换位相应select语句
ResultSet resultSet = statement.executeQuery(sql);

while (resultSet.next()) {
String url = resultSet.getString("url");
urlList.add(url);
System.out.println(url);
}

JdbcUtil.free(resultSet, statement, connection);
} catch (SQLException e) {
e.printStackTrace();
}

return urlList;
}

}

package com.ronniewang.utilities;

import java.sql.*;
import javax.sql.*;

/**
* 连接mysql数据库的工具类，用来作为DownloadPicture进行数据库连接的辅助类
* @author Administrator
*
*/
public final class JdbcUtil {
//下列配置换成相应内容即可
private static String url = "jdbc:mysql://localhost:3306/test";
private static String user = "root";
private static String password = "123456";

private JdbcUtil() { }

static {
try {
Class.forName("com.mysql.jdbc.Driver");
} catch (ClassNotFoundException e) {
throw new ExceptionInInitializerError(e);
}
}

public static Connection getConnection() throws SQLException{
return DriverManager.getConnection(url, user, password);
}

public static void free(ResultSet rs, Statement st, Connection conn) {
try {
if (rs != null) {
rs.close();
}
} catch (SQLException e) {
e.printStackTrace();
} finally {
try {
if (st != null) {
st.close();
}
} catch (SQLException e) {
e.printStackTrace();
} finally {
if (conn != null) {
try {
conn.close();
} catch (SQLException e) {
e.printStackTrace();
}
}
}
}
}
}