随机数相关：
[code]
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.util.ArrayList;
import java.util.List;
import java.util.Properties;
public class Test {
public static void main(String[] args) throws IOException {
ReadFromFile("0", "1");
}
private static void ReadFromFile(String tag1, String tag2)
throws FileNotFoundException, IOException {
Properties prop = new Properties();
List<String> array = new ArrayList<String>();
InputStream in = new FileInputStream("D:/Ext/Demo/src/test.properties");
prop.load(in);
for (int i = 1; i <= prop.size(); i++) {
String index = prop.getProperty("" + i);
if (index.endsWith(tag1)) {
array.add(index);
}
}
if (array.isEmpty()) {
System.out.println("本次抽取完毕");
} else {
int random = (int) ((Math.random() * array.size()) + 1);
String test = array.get(random - 1);
for (int i = 1; i <= prop.size(); i++) {
String index = prop.getProperty("" + i);
if (index.equals(test)) {
writeToFile(prop, i, index, tag2);
}
}
System.out.println("中奖者是： " + test.split(tag1)[0]);
}
}
private static String writeToFile(Properties prop, int random, String man,
String tag2) throws FileNotFoundException, IOException {
String test;
String target;
test = man.substring(0, man.length() - 1);
target = test + tag2;
prop.setProperty("" + random, target);
OutputStream out = new FileOutputStream(
"D:/Ext/Demo/src/test.properties");
prop.store(out, "copyright by diaoer");
out.close();
return test;
}
}
[/code]
