builder pattern

java-examples/src/main/java/cn/edu/jxnu/examples/design/builder/UserDto.java

+package cn.edu.jxnu.examples.design.builder;
+
+/**
+ * builder模式
+ *
+ * @author 梦境迷离
+ * @version 1.0 2018-08-27
+ */
+public class UserDto {
+
+    private final String firstName;     // 必传参数
+    private final String lastName;      // 必传参数
+    private final int age;              // 可选参数
+    private final String phone;         // 可选参数
+    private final String address;       // 可选参数
+
+    private UserDto(UserBuilder builder) {
+        this.firstName = builder.firstName;
+        this.lastName = builder.lastName;
+        this.age = builder.age;
+        this.phone = builder.phone;
+        this.address = builder.address;
+    }
+
+    public String getFirstName() {
+        return firstName;
+    }
+
+    public String getLastName() {
+        return lastName;
+    }
+
+    public int getAge() {
+        return age;
+    }
+
+    public String getPhone() {
+        return phone;
+    }
+
+    public String getAddress() {
+        return address;
+    }
+
+    //因为有两个必填参数
+    public static UserBuilder newUserBuilder(String fn, String ln) {
+        return new UserBuilder(fn, ln);
+    }
+
+    //委托UserBuilder来构造User对象
+    public static class UserBuilder {
+        private final String firstName;
+        private final String lastName;
+        private int age;
+        private String phone;
+        private String address;
+
+        public UserBuilder(String firstName, String lastName) {
+            this.firstName = firstName;
+            this.lastName = lastName;
+        }
+
+        public UserBuilder setAge(int age) {
+            this.age = age;
+            return this;
+        }
+
+        public UserBuilder setPhone(String phone) {
+            this.phone = phone;
+            return this;
+        }
+
+        public UserBuilder setAddress(String address) {
+            this.address = address;
+            return this;
+        }
+
+        public UserDto builder() {
+            return new UserDto(this);
+        }
+    }
+
+    public static void main(String[] args) {
+        UserDto userDto = UserDto
+                .newUserBuilder("hello", "world")
+                .setAge(12)
+                .setPhone("110")
+                .setAddress("beijing")
+                .builder();
+        System.out.println(userDto);
+    }
+}