java - 在 Android 应用程序中读取 CSV 文件

Question

我正在开发一个概念验证应用程序，以便我可以在我正在制作的更大的应用程序中实现该功能。我对 Java 和 Android Dev 有点陌生，但希望这个问题不会太简单或太复杂。

基本上，我试图从 CSV 文件中读取字符串列表，并使其可用于在应用程序的主 Activity 中显示列表。

我正在使用外部类来读取 CSV 文件。这是类代码:

CSVFile.java

package com.yourtechwhiz.listdisplay;

import android.util.Log;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.util.ArrayList;
import java.util.List;

public class CSVFile {
    InputStream inputStream;

    public CSVFile(InputStream inputStream){
        this.inputStream = inputStream;
    }

    public List read(){
        List resultList = new ArrayList();
        BufferedReader reader = new BufferedReader(new InputStreamReader(inputStream));
        try {
            String csvLine;
            while ((csvLine = reader.readLine()) != null) {
                String[] row = csvLine.split(",");
                resultList.add(row);
                Log.d("VariableTag", row[0].toString());
            }
        }
        catch (IOException ex) {
            throw new RuntimeException("Error in reading CSV file: "+ex);
        }
        finally {
            try {
                inputStream.close();
            }
            catch (IOException e) {
                throw new RuntimeException("Error while closing input stream: "+e);
            }
        }
        return resultList;
    }
}

这是我的主要 Activity 代码:

MainActivity.java

package com.yourtechwhiz.listdisplay;

import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.util.Log;
import android.widget.ArrayAdapter;
import android.widget.ListView;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.util.ArrayList;
import java.util.List;

public class MainActivity extends AppCompatActivity {

    // Array of strings that's used to display on screen
    String[] mobileArray = {"Android","IPhone","WindowsMobile","Blackberry",
            "WebOS","Ubuntu","Windows7","Max OS X"};

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        prepArray();

        //Display List on Activity
        ArrayAdapter adapter = new ArrayAdapter<String>(this,
                R.layout.activity_listview, mobileArray);
        ListView listView = (ListView) findViewById(R.id.mobile_list);
        listView.setAdapter(adapter);

    }

    //Get list of strings from CSV ready to use
    private void prepArray() {

        InputStream inputStream = getResources().openRawResource(R.raw.strings);
        CSVFile csvFile = new CSVFile(inputStream);
        List myList = csvFile.read();

        //This is where it has an error
        //Set first array in myList to this new array myArray
        String[] myArray = myList.get(0);

    }

}

我实际上还没有到设置 mobileArray 数组的地步。现在我只是想从列表对象 myList 中“提取”信息...

谁能给我解释一下这是怎么做到的？也许我只是不完全理解 List 类型。似乎在 CSVFile 读取方法中返回 resultList 时，它作为由 String 数组对象组成的 List 对象返回。但我似乎无法让它像那样工作。

感谢任何帮助!

最终编辑(工作代码)

private void prepArray() {

        try{
            CSVReader reader = new CSVReader(new InputStreamReader(getResources().openRawResource(R.raw.strings)));//Specify asset file name
            String [] nextLine;
            while ((nextLine = reader.readNext()) != null) {
                // nextLine[] is an array of values from the line
                System.out.println(nextLine[0] + nextLine[1] + "etc...");
                Log.d("VariableTag", nextLine[0]);
            }
        }catch(Exception e){
            e.printStackTrace();
            Toast.makeText(this, "The specified file was not found", Toast.LENGTH_SHORT).show();
        }

    }

编辑

现在我的 prepArray 函数如下所示:

    private void prepArray() {

        try{
            String csvfileString = this.getApplicationInfo().dataDir + File.separatorChar + "strings.csv"
            File csvfile = new File(csvfileString);
            CSVReader reader = new CSVReader(new FileReader("csvfile.getAbsolutePath()"));
            String [] nextLine;
            while ((nextLine = reader.readNext()) != null) {
                // nextLine[] is an array of values from the line
                System.out.println(nextLine[0] + nextLine[1] + "etc...");
            }
        }catch(FileNotFoundException e){
            e.printStackTrace();
            Toast.makeText(this, "The specified file was not found", Toast.LENGTH_SHORT).show();
        }

    }

仍然会产生 FileNotFoundException。

编辑 2/3

这是我在实际手机上运行应用程序时生成的日志，其中 strings.csv 位于字符串 (src\main\assets\strings\strings.csv) 的子文件夹中，其中包含您请求的代码更改:

03/27 17:44:01: Launching app
        $ adb push C:\Users\Roy\AndroidStudioProjects\ListDisplay\app\build\outputs\apk\app-debug.apk /data/local/tmp/com.yourtechwhiz.listdisplay
        $ adb shell pm install -r "/data/local/tmp/com.yourtechwhiz.listdisplay"
        pkg: /data/local/tmp/com.yourtechwhiz.listdisplay
        Success


        $ adb shell am start -n "com.yourtechwhiz.listdisplay/com.yourtechwhiz.listdisplay.MainActivity" -a android.intent.action.MAIN -c android.intent.category.LAUNCHER -D
        Connecting to com.yourtechwhiz.listdisplay
        D/HyLog: I : /data/font/config/sfconfig.dat, No such file or directory (2)
        D/HyLog: I : /data/font/config/dfactpre.dat, No such file or directory (2)
        D/HyLog: I : /data/font/config/sfconfig.dat, No such file or directory (2)
        W/ActivityThread: Application com.yourtechwhiz.listdisplay is waiting for the debugger on port 8100...
        I/System.out: Sending WAIT chunk
        I/dalvikvm: Debugger is active
        I/System.out: Debugger has connected
        I/System.out: waiting for debugger to settle...
        Connected to the target VM, address: 'localhost:8609', transport: 'socket'
        I/System.out: waiting for debugger to settle...
        I/System.out: waiting for debugger to settle...
        I/System.out: waiting for debugger to settle...
        I/System.out: waiting for debugger to settle...
        I/System.out: waiting for debugger to settle...
        I/System.out: waiting for debugger to settle...
        I/System.out: waiting for debugger to settle...
        I/System.out: debugger has settled (1498)
        I/dalvikvm: Could not find method android.view.Window$Callback.onProvideKeyboardShortcuts, referenced from method android.support.v7.view.WindowCallbackWrapper.onProvideKeyboardShortcuts
        W/dalvikvm: VFY: unable to resolve interface method 16152: Landroid/view/Window$Callback;.onProvideKeyboardShortcuts (Ljava/util/List;Landroid/view/Menu;I)V
        D/dalvikvm: VFY: replacing opcode 0x72 at 0x0002
        W/dalvikvm: VFY: unable to find class referenced in signature (Landroid/view/SearchEvent;)
        I/dalvikvm: Could not find method android.view.Window$Callback.onSearchRequested, referenced from method android.support.v7.view.WindowCallbackWrapper.onSearchRequested
        W/dalvikvm: VFY: unable to resolve interface method 16154: Landroid/view/Window$Callback;.onSearchRequested (Landroid/view/SearchEvent;)Z
        D/dalvikvm: VFY: replacing opcode 0x72 at 0x0002
        I/dalvikvm: Could not find method android.view.Window$Callback.onWindowStartingActionMode, referenced from method android.support.v7.view.WindowCallbackWrapper.onWindowStartingActionMode
        W/dalvikvm: VFY: unable to resolve interface method 16158: Landroid/view/Window$Callback;.onWindowStartingActionMode (Landroid/view/ActionMode$Callback;I)Landroid/view/ActionMode;
        D/dalvikvm: VFY: replacing opcode 0x72 at 0x0002
        I/dalvikvm: Could not find method android.content.res.TypedArray.getChangingConfigurations, referenced from method android.support.v7.widget.TintTypedArray.getChangingConfigurations
        W/dalvikvm: VFY: unable to resolve virtual method 455: Landroid/content/res/TypedArray;.getChangingConfigurations ()I
        D/dalvikvm: VFY: replacing opcode 0x6e at 0x0002
        I/dalvikvm: Could not find method android.content.res.TypedArray.getType, referenced from method android.support.v7.widget.TintTypedArray.getType
        W/dalvikvm: VFY: unable to resolve virtual method 477: Landroid/content/res/TypedArray;.getType (I)I
        D/dalvikvm: VFY: replacing opcode 0x6e at 0x0008
        I/dalvikvm: Could not find method android.widget.FrameLayout.startActionModeForChild, referenced from method android.support.v7.widget.ActionBarContainer.startActionModeForChild
        W/dalvikvm: VFY: unable to resolve virtual method 16589: Landroid/widget/FrameLayout;.startActionModeForChild (Landroid/view/View;Landroid/view/ActionMode$Callback;I)Landroid/view/ActionMode;
        D/dalvikvm: VFY: replacing opcode 0x6f at 0x0002
        I/dalvikvm: Could not find method android.content.Context.getColorStateList, referenced from method android.support.v7.content.res.AppCompatResources.getColorStateList
        W/dalvikvm: VFY: unable to resolve virtual method 269: Landroid/content/Context;.getColorStateList (I)Landroid/content/res/ColorStateList;
        D/dalvikvm: VFY: replacing opcode 0x6e at 0x0006
        I/dalvikvm: Could not find method android.content.res.Resources.getDrawable, referenced from method android.support.v7.widget.ResourcesWrapper.getDrawable
        W/dalvikvm: VFY: unable to resolve virtual method 418: Landroid/content/res/Resources;.getDrawable (ILandroid/content/res/Resources$Theme;)Landroid/graphics/drawable/Drawable;
        D/dalvikvm: VFY: replacing opcode 0x6e at 0x0002
        I/dalvikvm: Could not find method android.content.res.Resources.getDrawableForDensity, referenced from method android.support.v7.widget.ResourcesWrapper.getDrawableForDensity
        W/dalvikvm: VFY: unable to resolve virtual method 420: Landroid/content/res/Resources;.getDrawableForDensity (IILandroid/content/res/Resources$Theme;)Landroid/graphics/drawable/Drawable;
        D/dalvikvm: VFY: replacing opcode 0x6e at 0x0002
        E/dalvikvm: Could not find class 'android.graphics.drawable.RippleDrawable', referenced from method android.support.v7.widget.AppCompatImageHelper.hasOverlappingRendering
        W/dalvikvm: VFY: unable to resolve instanceof 140 (Landroid/graphics/drawable/RippleDrawable;) in Landroid/support/v7/widget/AppCompatImageHelper;
        D/dalvikvm: VFY: replacing opcode 0x20 at 0x000c
        W/System.err: java.io.FileNotFoundException: /csvfile.getAbsolutePath(): open failed: ENOENT (No such file or directory)
        W/System.err:     at libcore.io.IoBridge.open(IoBridge.java:462)
        W/System.err:     at java.io.FileInputStream.<init>(FileInputStream.java:78)
        W/System.err:     at java.io.FileInputStream.<init>(FileInputStream.java:105)
        W/System.err:     at java.io.FileReader.<init>(FileReader.java:66)
        W/System.err:     at com.yourtechwhiz.listdisplay.MainActivity.prepArray(MainActivity.java:43)
        W/System.err:     at com.yourtechwhiz.listdisplay.MainActivity.onCreate(MainActivity.java:26)
        W/System.err:     at android.app.Activity.performCreate(Activity.java:5287)
        W/System.err:     at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1087)
        W/System.err:     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2145)
        W/System.err:     at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2231)
        W/System.err:     at android.app.ActivityThread.access$700(ActivityThread.java:139)
        W/System.err:     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1401)
        W/System.err:     at android.os.Handler.dispatchMessage(Handler.java:102)
        W/System.err:     at android.os.Looper.loop(Looper.java:137)
        W/System.err:     at android.app.ActivityThread.main(ActivityThread.java:5082)
        W/System.err:     at java.lang.reflect.Method.invokeNative(Native Method)
        W/System.err:     at java.lang.reflect.Method.invoke(Method.java:515)
        W/System.err:     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:782)
        W/System.err:     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:598)
        W/System.err:     at dalvik.system.NativeStart.main(Native Method)
        W/System.err: Caused by: libcore.io.ErrnoException: open failed: ENOENT (No such file or directory)
        W/System.err:     at libcore.io.Posix.open(Native Method)
        W/System.err:     at libcore.io.BlockGuardOs.open(BlockGuardOs.java:110)
        W/System.err:     at libcore.io.IoBridge.open(IoBridge.java:446)
        W/System.err:   ... 19 more
        I/Adreno-EGL: <qeglDrvAPI_eglInitialize:385>: EGL 1.4 QUALCOMM build:  ()
        OpenGL ES Shader Compiler Version: E031.24.00.01
        Build Date: 12/27/13 Fri
        Local Branch: qualcomm_only
        Remote Branch:
        Local Patches:
        Reconstruct Branch:
        D/OpenGLRenderer: Enabling debug mode 0
        D/OpenGLRenderer: GL error from OpenGLRenderer: 0x502
        E/OpenGLRenderer:   GL_INVALID_OPERATION

Answer 1

尝试 OpenCSV - 它会让您的生活更轻松。

首先，将这个包添加到你的 gradle 依赖项中，如下所示

implementation 'com.opencsv:opencsv:4.6'

然后你可以做

import com.opencsv.CSVReader;
import java.io.IOException;
import java.io.FileReader;


...

try {
    CSVReader reader = new CSVReader(new FileReader("yourfile.csv"));
    String[] nextLine;
    while ((nextLine = reader.readNext()) != null) {
        // nextLine[] is an array of values from the line
        System.out.println(nextLine[0] + nextLine[1] + "etc...");
    }
} catch (IOException e) {

}

或

CSVReader reader = new CSVReader(new FileReader("yourfile.csv"));
List myEntries = reader.readAll();

---

评论后编辑

try {
    File csvfile = new File(Environment.getExternalStorageDirectory() + "/csvfile.csv");
    CSVReader reader = new CSVReader(new FileReader(csvfile.getAbsolutePath()));
    String[] nextLine;
    while ((nextLine = reader.readNext()) != null) {
        // nextLine[] is an array of values from the line
        System.out.println(nextLine[0] + nextLine[1] + "etc...");
    }
} catch (Exception e) {
    e.printStackTrace();
    Toast.makeText(this, "The specified file was not found", Toast.LENGTH_SHORT).show();
}

如果您想将 .csv 文件与应用程序打包在一起，并在应用程序安装时将其安装在内部存储中，请在您的项目中创建一个 assets 文件夹 src/main 文件夹(例如，c:\myapp\app\src\main\assets\)，并将 .csv 文件放在那里，然后在您的 Activity 中像这样引用它:

String csvfileString = this.getApplicationInfo().dataDir + File.separatorChar + "csvfile.csv"
File csvfile = new File(csvfileString);