桥接模式下的本地数据加载

项目中我们可以加载assets文件夹下的xml文件、txt文件、图片文件，也可加载sd卡下xml文件、txt文件、图片文件。如图

这里有两个变化的维度，文件地址和数据格式。我将抽象与实现分离构建本地数据加载。

代码：数据

public interface Data<D> {    /**     * 加载数据流     * @param inputStream     */    void load(InputStream inputStream);    /**     * 数据对象     * @return     */    D get();    /**     * 数据对象大小     * @return     */    int size();}

抽象数据

public abstract class AbsData<D> implements Data<D> {    protected Path path;    public AbsData(Path path) {        this.path = path;        load(path.loadInputStream());    }    //关闭流    protected void close(Closeable closeable) {        if (closeable != null) {            try {                closeable.close();            } catch (IOException ex) {            }        }    }}

数据地址

public interface Path {    /**     * 路径     *     * @return     */    void setDataPath(String path);    /**     * 获取流     *     * @return     */    InputStream loadInputStream();}

抽象地址

public abstract class AbsPath implements Path {    protected String path;    @Override    public void setDataPath(String path) {        this.path = path;    }}

Assets文件夹

public class AssetPath extends AbsPath {    private Context context;    public AssetPath(Context context) {        this.context = context;    }    @Override    public InputStream loadInputStream() {        try {            return context.getAssets().open(path);        } catch (IOException e) {            e.printStackTrace();        }        return null;    }}

sd卡

public class FilePath extends AbsPath {    @Override    public InputStream loadInputStream() {        try {            File urlFile = new File(path);            return new FileInputStream(urlFile);        } catch (FileNotFoundException e) {            e.printStackTrace();        }        return null;    }}

位图数据

public class BitmapData extends AbsData<Bitmap> {    private Bitmap data;    public BitmapData(Path path) {        super(path);    }    @Override    public void load(InputStream inputStream) {        data = BitmapFactory.decodeStream(inputStream);    }    @Override    public Bitmap get() {        return data;    }    @Override    public int size() {        return data.getByteCount();    }}

字符数据

public class StringData extends AbsData<String> {    protected String data;    public StringData(Path path) {        super(path);    }    @Override    public void load(InputStream inputStream) {        BufferedReader reader = new BufferedReader(new InputStreamReader(inputStream));        StringBuilder sb = new StringBuilder();        String line = null;        try {            while ((line = reader.readLine()) != null) {                sb.append(line + "\n");            }        } catch (IOException e) {            e.printStackTrace();        } finally {            close(inputStream);        }        data = sb.toString();    }    @Override    public String get() {        return data;    }    @Override    public int size() {        return data.length();    }}

抽象xml数据

public abstract class XmlData<T> extends AbsData {    protected T data;    public XmlData(Path path) {        super(path);    }    @Override    public void load(InputStream inputStream) {        try {            DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();            DocumentBuilder builder = factory.newDocumentBuilder();            data = parser(builder.parse(inputStream));        } catch (ParserConfigurationException e) {            e.printStackTrace();        } catch (SAXException e) {            e.printStackTrace();        } catch (IOException e) {            e.printStackTrace();        } finally {          close(inputStream);        }    }    @Override    public T get() {        return data;    }    protected abstract T parser(Document parse);}

xml数据

public class RiverXml extends XmlData<List<River>> {    public RiverXml(Path path) {        super(path);    }    @Override    public int size() {        return data.size();    }    @Override    protected List<River> parser(Document document) {        //找到根Element        data = new ArrayList<>();        Element root = document.getDocumentElement();        NodeList nodes = root.getElementsByTagName("river");        //遍历根节点所有子节点,rivers 下所有river        River river;        for (int i = 0; i < nodes.getLength(); i++) {            river = new River();            Element riverElement = (Element) (nodes.item(i));            river.setName(riverElement.getAttribute("name"));            river.setLength(Integer.parseInt(riverElement.getAttribute("length")));            Element introduction = (Element) riverElement.getElementsByTagName("introduction").item(0);            river.setIntroduction(introduction.getFirstChild().getNodeValue());            Element imageUrl = (Element) riverElement.getElementsByTagName("imageurl").item(0);            river.setImageurl(imageUrl.getFirstChild().getNodeValue());            data.add(river);        }        return data;    }

River类

public class River implements Serializable {    private int length;    private String imageurl;    private String name;    private String introduction;    public String getName() {        return name;    }    public void setName(String name) {        this.name = name;    }    public int getLength() {        return length;    }    public void setLength(int length) {        this.length = length;    }    public String getIntroduction() {        return introduction;    }    public void setIntroduction(String introduction) {        this.introduction = introduction;    }    public String getImageurl() {        return imageurl;    }    public void setImageurl(String imageurl) {        this.imageurl = imageurl;    }}

测试xml文件

<?xml version="1.0" encoding="utf-8"?><rivers>    <river name="灵渠" length="605">        <introduction>            灵渠在广西壮族自治区兴安县境内，是世界上最古老的运河之一，有着“世界古代水利建筑明珠”的美誉。        </introduction>        <imageurl>            http://imgsrc.baidu.com/baike/pic/item/389aa8fdb7b8322e08244d3c.jpg        </imageurl>    </river>    <river name="胶莱运河" length="200">        <introduction>            胶莱运河南起黄海灵山海口，北抵渤海三山岛，流经现胶南、胶州、平度、高密、昌邑和莱州等，全长200公里。        </introduction>        <imageurl>            http://imgsrc.baidu.com/baike/pic/item/389aa8fdb7b8322e08244d3c.jpg        </imageurl>    </river>    <river name="苏北灌溉总渠" length="168">        <introduction>            位于淮河下游江苏省北部，西起洪泽湖边的高良涧，流经洪泽，青浦、淮安，阜宁、射阳，滨海等六县(区)，东至扁担港口入海的大型人工河道。        </introduction>        <imageurl>            http://imgsrc.baidu.com/baike/pic/item/389aa8fdb7b8322e08244d3c.jpg        </imageurl>    </river></rivers>

代码调用

        FilePath filePath = new FilePath();        AssetPath assetPath = new AssetPath(this);        filePath.setDataPath("/sdcard/river.xml");        assetPath.setDataPath("river.xml");        RiverXml assetData = new RiverXml(assetPath);        RiverXml fileData = new RiverXml(filePath);        L.d(assetData.get().get(1).getName());        L.d(fileData.get().get(2).getName());        assetPath.setDataPath("temp_license.txt");        StringData stringData = new StringData(assetPath);        L.d(stringData.get());

结果

07-18 09:45:27.119 636-636/com.aiju.myapplication D/AiJu: 胶莱运河07-18 09:45:27.119 636-636/com.aiju.myapplication D/AiJu: 苏北灌溉总渠07-18 09:45:27.121 636-636/com.aiju.myapplication D/AiJu: assets文本测试