Properties的有序读写

使用java.util.Properties提供的类，读取properties文件的时候，读出来的是乱序的

如下边的情况

import java.io.*;
import java.util.Arrays;
import java.util.Enumeration;
import java.util.List;
import java.util.Properties;

public class PropertyDemo {

    public static List<String> old = Arrays.asList("自来水","纯净水", "矿泉水","山泉水" );

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

    public static void initType() {

        String path = System.getProperty("user.dir").replaceAll("\\", "/");
        path = path + "/waterType.properties";
        File file = new File(path);
        Properties properties = new Properties();
        if (!file.exists()) {
            try {
                FileOutputStream oFile = new FileOutputStream(path, true);
                int i = 0;
                int len = old.size();
                for (; i < len; i++) {
                    properties.setProperty(String.valueOf(i + 1), old.get(i));
                }
                properties.store(oFile, "");
                oFile.close();
            } catch (IOException e) {
                e.printStackTrace();
            }

        }
        try {
            InputStream in = new BufferedInputStream(new FileInputStream(path));
            properties.load(in);
            in.close();
        } catch (IOException ex) {
            ex.printStackTrace();
        }

        //遍历
        Enumeration<?> e= properties.propertyNames();
        while (e.hasMoreElements()){
            String key = (String) e.nextElement();
            String value = properties.getProperty(key);
            System.out.println(key + "=" + value);
        }

    }
}

输出

4=山泉水
3=矿泉水
2=纯净水
1=自来水

保存到文件的顺序也是如此

那如果想是有序的，怎么办呢？

自定义一个Properties 类

import java.util.*;

public class OrderedProperties extends Properties {

    private final LinkedHashSet<Object> keys = new LinkedHashSet<Object>();

    public Enumeration<Object> keys() {
        return Collections.<Object>enumeration(keys);
    }

    public Object put(Object key, Object value) {
        keys.add(key);
        return super.put(key, value);
    }

    public Set<Object> keySet() {
        return keys;
    }

    public Set<String> stringPropertyNames() {
        Set<String> set = new LinkedHashSet<String>();
        for (Object key : this.keys) {
            set.add((String) key);
        }
        return set;
    }

}

使用

import java.io.*;
import java.util.*;

public class PropertyDemo {

    public static List<String> old = Arrays.asList("自来水","纯净水", "矿泉水","山泉水" );

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

    public static void initType() {

        String path = System.getProperty("user.dir").replaceAll("\\", "/");
        path = path + "/waterType.properties";
        File file = new File(path);
        Properties properties = new OrderedProperties();
        if (!file.exists()) {
            try {
                FileOutputStream oFile = new FileOutputStream(path, true);
                int i = 0;
                int len = old.size();
                for (; i < len; i++) {
                    properties.setProperty(String.valueOf(i + 1), old.get(i));
                }
                properties.store(oFile, "");
                oFile.close();
            } catch (IOException e) {
                e.printStackTrace();
            }

        }
        try {
            InputStream in = new BufferedInputStream(new FileInputStream(path));
            properties.load(in);
            in.close();
        } catch (IOException ex) {
            ex.printStackTrace();
        }

        //遍历
        Set<String> e = properties.stringPropertyNames();
        for (String one : e) {
            String key = one;
            String value = properties.getProperty(one);
            System.out.println(key + "=" + value);
        }

    }
}

输出

1=自来水
2=纯净水
3=矿泉水
4=山泉水

保存到文件的顺序也是如此

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