原 荐 OSGL 工具库 - 类型转换的艺术

Y y = $.convert(x).to(Y.class)

String s = "60";
int n = $.convert(s).to(Integer.class); // 60
n = $.convert(s).toInteger(); // 60
n = $.convert(s).toInt(); // 60
s = $.convert(n).toString(); // "60"
s = $.convert(n).to(String.class); // "60"

// 这里 hint 的意思是 radix
n = $.convert("FF").hint(16).toInt(); // 255
// 这里 hint  的意思是日期格式
Date date = $.convert("06 Apr 2018").hint("dd MMM yyyy").toDate(); // 2018-04-06
String dateStr = $.convert(date).hint("yyyy-MM-dd").toString(); // 2018-04-06

enum Code {
    AB, bc, Red;
}
Code code; 
code = $.convert("AB").to(Code.class); // Code.AB
code = $.convert("ab").caseInsensitivie().to(Code.class); // Code.AB

int n = $.convert(null).to(int.class); // 0
n = $.convert(null).to
Integer N = $.convert(null).to(Integer.class); // null

n = $.convert(null).defaultTo(5).toInt(); // 5
n = $.convert("2").defaultTo(5).toInt(); // 2

// 例1: 不用日期函数来转换日期格式:
// 06/Apr/2018 -> 2018-04-06
s = $.convert("06/Apr/2018")
        .hint("dd/MMM/yyyy")
        .pipeline(Date.class)
        .hint("yyyy-MM-dd")
        .toString(); // 2018-04-06

// 例2: 日期转到byte[]
byte[] ba = $.convert(new Date()).pipeline(String.class).to(byte[].class);

ba = $.convert(new Date()).to(byte[].class);

public class MyFrom {
    public String id;

    public MyFrom(String id) {
        this.id = id;
    }

    @Override
    public boolean equals(Object o) {
        if (this == o) return true;
        if (o == null || getClass() != o.getClass()) return false;
        MyFrom myFrom = (MyFrom) o;
        return id != null ? id.equals(myFrom.id) : myFrom.id == null;
    }

    @Override
    public int hashCode() {
        return id != null ? id.hashCode() : 0;
    }
}

public class MyTo {
    public String id;

    public MyTo(String id) {
        this.id = id;
    }

    @Override
    public boolean equals(Object o) {
        if (this == o) return true;
        if (o == null || getClass() != o.getClass()) return false;
        MyTo MyTo = (MyTo) o;
        return id != null ? id.equals(MyTo.id) : MyTo.id == null;
    }

    @Override
    public int hashCode() {
        return id != null ? id.hashCode() : 0;
    }
}

// MyFrom -> MyTo
public class MyConverter extends $.TypeConverter<MyFrom, MyTo> {
    @Override
    public MyTo convert(MyFrom myFrom) {
        return new MyTo(myFrom.id);
    }
}
// String -> MyFrom
public class MyConverter extends $.TypeConverter<String, MyFrom> {
    @Override
    public MyFrom convert(String s) {
        return new MyFrom(s);
    }
}

TypeConverterRegistry.INSTANCE
    .register(new MyConverter())
    .register(new StringToMyFrom());

String s = "abc";
MyFrom from = new MyFrom(s);
MyTo to = $.convert(from).to(MyTo.class);

// 通过隐式管道转换 String 到 myTo
to = $.convert(s).to(MyTo.class);