day16

jdbc.properties

@@ -0,0 +1 @@
+user_name = admin;

src/main/java/com/sf/javase/day16/T.java

@@ -0,0 +1,178 @@
+package com.sf.javase.day16;
+
+import org.junit.jupiter.api.Test;
+
+import java.io.FileInputStream;
+import java.io.IOException;
+import java.util.*;
+import java.util.function.BiConsumer;
+import java.util.function.BiFunction;
+
+/**
+ * Map
+ *
+ */
+public class T {
+    @Test
+    public void t1(){
+        Map<String,String> map = new HashMap();
+        map.put("code","200");
+        map.put("msg","success");
+        System.out.println("----"+ map);
+//        Set<Map.Entry<String, String>> entries = map.entrySet();
+//        for (Map.Entry<String, String> entry : entries) {
+//            String key = entry.getKey();
+//            String value = entry.getValue();
+//            System.out.println(key+"===="+value);
+//            String error = entry.setValue("error");
+//            String value1 = entry.getValue();
+//            System.out.println(key+"===="+value1);
+//            System.out.println(error);
+//        }
+
+        Set<String> key = map.keySet();
+        map.get(key);
+        System.out.println("-------------");
+        map.forEach(new BiConsumer<String, String>() {
+            @Override
+            public void accept(String s, String s2) {
+                System.out.println("key--"+s);
+                System.out.println("value=="+s2);
+            }
+        });
+
+        System.out.println("-------------");
+        //第二种
+        Iterator<Map.Entry<String, String>> iterator = map.entrySet().iterator();
+        while (iterator.hasNext()){
+            Map.Entry<String, String> entry = iterator.next();
+            entry.getKey();
+            entry.getValue();
+        }
+
+        // 第三种
+        for (Map.Entry<String, String> entry : map.entrySet()) {
+            entry.getValue();
+            entry.getKey();
+        }
+
+        // 只能获取value     只能获取key  keyset
+        for (String value : map.values()) {
+            System.out.println(value);
+        }
+    }
+
+    @Test
+    public void t2(){
+        Map<String,String> map = new HashMap<>();
+        map.put("userName","admin");
+        map.put("pwd","123456");
+        map.put("pwd1","123456");
+        Map<String,String> map1 = new HashMap<>();
+        map1.putAll(map);
+        System.out.println(map1);
+        String pwd1 = map.remove("pwd1");
+        System.out.println(pwd1);
+        System.out.println(map);
+        map1.clear();
+        System.out.println(map1);
+        boolean userName = map.containsKey("userName");
+        System.out.println(userName);
+        boolean admin = map.containsValue("admin");
+        System.out.println(admin);
+        boolean equals = map.equals(map1);
+        System.out.println(equals);
+    }
+
+
+    @Test
+    public void t4(){
+        //  实现定制排序
+        TreeMap<String,Object> map = new TreeMap<>(new Comparator<String>() {
+            @Override
+            public int compare(String o1, String o2) {
+                return o1.compareTo(o2);
+            }
+        });
+        map.put("CC",45);
+        map.put("MM",78);
+        map.put("DD",56);
+        map.put("GG",89);
+        map.put("JJ",99);
+        System.out.println(map);
+    }
+
+    /**
+     * 自然排序、
+     * User
+     */
+    @Test
+    public void t5(){
+        TreeMap<User,String> treeMap = new TreeMap();
+        treeMap.put(new User(2,"zs"),"user1");
+        treeMap.put(new User(1,"li"),"user2");
+        treeMap.put(new User(3,"ww"),"user3");
+        System.out.println(treeMap);
+    }
+
+    @Test
+    public void t6(){
+        Hashtable<String,String> hashtable = new Hashtable();
+        hashtable.put("user","admin");
+        hashtable.put("pwd","123");
+//        hashtable.replaceAll(new BiFunction<String, String, String>() {
+//            @Override  // 满足key = s  value = s2     将value替换成新的返回值
+//            public String apply(String s, String s2) {
+////                String admin1 = s2.replaceAll(s2, "admin1");
+////                System.out.println("key  = "+admin1);
+////                System.out.println("value = "+s2);
+//                return "admin1";
+//            }
+//        });
+//        System.out.println(hashtable);
+        hashtable.compute("user1", new BiFunction<String, String, String>() {
+            @Override   //  key   如果存在  更改value值    若不存在  新增一条记录entry[key  返回值]
+            public String apply(String s, String s2) {
+                return "qqq";
+            }
+        });
+        System.out.println(hashtable);
+    }
+
+
+    @Test
+    public void t7(){
+        Properties properties = new Properties();
+        properties.setProperty("username","admin");
+        System.out.println(properties.getProperty("username"));
+        System.out.println(properties.getProperty("user"));
+    }
+
+    @Test
+    public void t8(){
+        Properties properties = System.getProperties();
+        String property = properties.getProperty("file.encoding");
+        System.out.println(property);
+        properties.setProperty("file.encoding","GBK");
+        System.out.println(properties.getProperty("file.encoding"));
+        String property1 = System.getProperty("file.encoding");
+        System.out.println(property1);
+    }
+
+    @Test
+    public void t9() throws IOException {
+        Properties properties = new Properties();
+        // jdbc.properties
+        properties.load(new FileInputStream("jdbc.properties"));  //加载
+        String username = properties.getProperty("user_name");
+        System.out.println(username);
+    }
+
+    public static void main(String[] args) throws IOException {
+        Properties properties = new Properties();
+        // jdbc.properties
+        properties.load(new FileInputStream("jdbc.properties"));  //加载
+        String username = properties.getProperty("user_name");
+        System.out.println(username);
+    }
+}

src/main/java/com/sf/javase/day16/User.java

@@ -0,0 +1,29 @@
+package com.sf.javase.day16;
+
+public class User implements Comparable{
+    private int id;
+    private String name;
+
+    public User(int id, String name) {
+        this.id = id;
+        this.name = name;
+    }
+
+    @Override
+    public String toString() {
+        return "User{" +
+                "id=" + id +
+                ", name='" + name + '\'' +
+                '}';
+    }
+
+    @Override
+    public int compareTo(Object o) {
+        if(o instanceof User){
+            User user = (User) o;
+            return this.id - user.id;
+        }else {
+            throw  new RuntimeException("类型异常");
+        }
+    }
+}