Symfoware

gradle + Kotlin で実行可能jarをビルドする

Kotlinプログラム

package sample
import java.sql.*
// MySQLへ接続
fun main(args: Array<String>) {
    var conn: Connection? = null
    var stmt: Statement? = null
    var rs: ResultSet? = null
    try {
        conn = DriverManager.getConnection("jdbc:mysql://192.168.1.101/sample", "admin", "P@ssw0rd")        
        stmt = conn.createStatement()
        rs = stmt.executeQuery("SELECT * FROM test")
        while (rs.next()) {
            println(rs.getInt("id"))
            println(rs.getString("value"))
        }
    } catch (e: Exception) {
        println(e)
    } finally {
        rs?.close()
        stmt?.close()
        conn?.close()
    }
    
}

gradle

Kotlin + gradleでMySQL 8.0に接続するプログラムを実行する

サンプルテーブルの作成

gradle

plugins {
    // Apply the Kotlin JVM plugin to add support for Kotlin.
    id 'org.jetbrains.kotlin.jvm' version '1.3.72'
    // Apply the application plugin to add support for building a CLI application.
    id 'application'
}
repositories {
    // Use jcenter for resolving dependencies.
    // You can declare any Maven/Ivy/file repository here.
    jcenter()
}
dependencies {
    // Align versions of all Kotlin components
    implementation platform('org.jetbrains.kotlin:kotlin-bom')
    // Use the Kotlin JDK 8 standard library.
    implementation 'org.jetbrains.kotlin:kotlin-stdlib-jdk8'
    // Use the Kotlin test library.
    testImplementation 'org.jetbrains.kotlin:kotlin-test'
    // Use the Kotlin JUnit integration.
    testImplementation 'org.jetbrains.kotlin:kotlin-test-junit'
    // ※ こちらの記載を追記
    compile group: 'mysql', name: 'mysql-connector-java', version: '8.0.20'
}
application {
    // Define the main class for the application.
    mainClassName = 'sample.AppKt'
}

接続サンプル

import java.sql.*
// MySQLへ接続
fun main(args: Array<String>) {
    var conn: Connection? = null
    var stmt: Statement? = null
    var rs: ResultSet? = null
    try {
        conn = DriverManager.getConnection("jdbc:mysql://192.168.1.101/sample", "admin", "P@ssw0rd")
        println("connect ok")
        stmt = conn.createStatement()
        rs = stmt.executeQuery("SELECT * FROM test")
        while (rs.next()) {
            println(rs.getInt("id"))
            println(rs.getString("value"))
        }
    } catch (e: Exception) {
        println(e)
    } finally {
        rs?.close()
        stmt?.close()
        conn?.close()
    }
    
}

データの追加、更新

import java.sql.*
// MySQLへ接続
fun main(args: Array<String>) {
    var conn: Connection? = null
    var stmt: Statement? = null
    var rs: ResultSet? = null
    try {
        conn = DriverManager.getConnection("jdbc:mysql://192.168.1.101/sample", "admin", "P@ssw0rd")
        println("connect ok")
        stmt = conn.createStatement()
        // データの追加
        stmt.execute("INSERT INTO test (id, value) VALUES (2, 'Kotlinから追加')")
        // データの更新
        stmt.execute("UPDATE test SET value = 'Kotlinで更新' WHERE id = 1")
        rs = stmt.executeQuery("SELECT * FROM test")
        while (rs.next()) {
            println(rs.getInt("id"))
            println(rs.getString("value"))
        }
    } catch (e: Exception) {
        println(e)
    } finally {
        rs?.close()
        stmt?.close()
        conn?.close()
    }
    
}

Kotlinで文字コードを指定し、CSVファイルを読み込む

テキストファイルを1行づつ読み込む

import java.io.*
import java.nio.file.*
// ファイル読み込み
fun main(args: Array<String>) {
    val file = Paths.get("sample.txt")
    var br: BufferedReader? = null
    try {
        br = Files.newBufferedReader(file)
        var text = br.readLine()
        while(text != null) {
            println(text)
            text = br.readLine()
        }
    } catch(e: Exception) {
        print(e)
    } finally {
        br?.close()
        print("ok")
    }
    
}

文字コードを指定してファイルを読み込む

import java.io.*
import java.nio.file.*
import java.nio.charset.*
// 文字コードを指定してファイル読み込み
fun main(args: Array<String>) {
    val file = Paths.get("sample_ms932.txt")
    var br: BufferedReader? = null
    try {
        // 第二引数で文字コードを指定
        br = Files.newBufferedReader(file, Charset.forName("MS932"))
        var text = br.readLine()
        while(text != null) {
            println(text)
            text = br.readLine()
        }
    } catch(e: Exception) {
        print(e)
    } finally {
        br?.close()
        print("ok")
    }
    
}

CSVファイルを読み込み

import java.io.*
import java.nio.file.*
import java.nio.charset.*
// CSVファイル読み込み
fun main(args: Array<String>) {
    val file = Paths.get("01HOKKAI.CSV")
    var br: BufferedReader? = null
    try {
        // 文字コードはms932
        br = Files.newBufferedReader(file, Charset.forName("MS932"))
        var text = br.readLine()
        while(text != null) {
            // 2:郵便番号, 6:都道府県, 7:市区町村, 8:番地
            val row = text.split(",").map{ it.trim('"') }
            println(row[2])
            println(row[6] + row[7] + row[8])
            text = br.readLine()
            // 確認のため1行目を表示したら停止
            break
        }
    } catch(e: Exception) {
        print(e)
    } finally {
        br?.close()
        print("ok")
    }
    
}

Kotlin 文字を指定し文字列前後の文字を除去する

trim

fun main(args: Array<String>) {
    val text = "-----abc123-------"
    println(text.trim('-'))
}

fun main(args: Array<String>) {
    val text = "--__==---abc123-------__=="
    println(text.trim('-', '_', '='))
}

Ubuntu 20.04にOpenJDK 14をインストール

apt