1. 程式人生 > >Java中列舉型別Enum的一種使用方式

Java中列舉型別Enum的一種使用方式

列舉類定義如下:


public enum Status {

    SCUUESS("1", "成功"), FAILED("2", "失敗");

    private String value;
    private String desc;

    public String getValue() {
        return value;
    }

    public void setValue(String value) {
        this.value = value;
    }

    public String getDesc() {
        return
desc; } public void setDesc(String desc) { this.desc = desc; } private Status(String value, String desc) { this.value = value; this.desc = desc; } }

使用的方式如下:


public class StutusTest {
    public static void main(String[] args) {

        System.out
.println(Status.SCUUESS.getValue()); System.out.println(Status.SCUUESS.getDesc()); System.out.println(Status.FAILED.getValue()); System.out.println(Status.FAILED.getDesc()); } }

這裡寫圖片描述

再比如,我們在操作資料庫的時候,通常使用數字儲存到資料庫中,但是在介面上顯示的時候,需要展示其中文意思,南無我們就可以通過下邊的方式:

public enum FlightType {

    OW(1
, "單程"), RT(2, "往返"); public Integer code; public String desc; FlightType(Integer code, String desc) { this.code = code; this.desc = desc; } public Integer getCode() { return code; } public void setCode(Integer code) { this.code = code; } public String getDesc() { return desc; } public void setDesc(String desc) { this.desc = desc; } public static FlightType getTypeByCode(Integer code) { FlightType defaultType = FlightType.OW; for (FlightType ftype : FlightType.values()) { if (ftype.code == code) { return ftype; } } return defaultType; } public static String getDescByCode(Integer code) { return getTypeByCode(code).desc; } }

這樣的話,我們就可以通過getDescByCode方法獲得其對應的中文。

另外,引數的個數是可以進行變化的,例如下邊:

public enum DatabaseType {
    unknown(null, null, null,null),
    mysql("com.mysql.jdbc.Driver", "com.mysql.jdbc.jdbc2.optional.MysqlXADataSource", "select 1",Dialect.MYSQL),
    h2("org.h2.Driver", "org.h2.jdbcx.JdbcDataSource", "select 1",Dialect.H2),
    oracle("oracle.jdbc.driver.OracleDriver", "oracle.jdbc.xa.client.OracleXADataSource", "select 1 from dual",Dialect.ORACLE);

    DatabaseType(String driverClassName, String xaDataSourceClassName, String testQuery,Dialect dialect) {
        this.driverClassName = driverClassName;
        this.testQuery = testQuery;
        this.xaDataSourceClassName = xaDataSourceClassName;
        this.dialect=dialect;
    }

    private final String testQuery;

    private final String driverClassName;

    private final String xaDataSourceClassName;
    private final Dialect dialect;
    public String getDriverClassName() {
        return driverClassName;
    }

    public String getXaDataSourceClassName() {
        return xaDataSourceClassName;
    }

    public String getTestQuery() {
        return testQuery;
    }

    public Dialect getDialect() {
        return dialect;
    }

    public static DatabaseType fromJdbcUrl(String url) {
        if (StringUtils.hasLength(url)) {
            Assert.isTrue(url.startsWith("jdbc"), "URL must start with 'jdbc'");
            String urlWithoutPrefix = url.substring("jdbc".length()).toLowerCase();
            for (DatabaseType driver : values()) {
                String prefix = ":" + driver.name().toLowerCase() + ":";
                if (driver != unknown && urlWithoutPrefix.startsWith(prefix)) {
                    return driver;
                }
            }
        }
        return unknown;
    }
}