java – 尝试使用自定义SerDe创建Hive表时出错

发布时间：2020-12-15 02:09:03 所属栏目：Java 来源：网络整理

导读：我有一个包含需要上传到Hive表的数据的文件.我写了一个自定义SerDe(它基本上是Hive已经提供的 Regex Serde的修改)来帮助我上传数据. 这是我写的SerDe package my.hive.customserde;public class FIASC2 extends AbstractSerDe { public static final Log LOG

我有一个包含需要上传到Hive表的数据的文件.我写了一个自定义SerDe(它基本上是Hive已经提供的 Regex Serde的修改)来帮助我上传数据.

这是我写的SerDe

package my.hive.customserde;

public class FIASC2 extends AbstractSerDe {

    public static final Log LOG = LogFactory.getLog(FIASC2.class.getName());

    int colwidths[] = {1,10,6,12,8,14,16,2,19,1};
    String outputformat = "%1$s %2$s %3$s %4$s %5$s %6$s %7$s %8$s %9$s %10$s %11$s %12$s %13$s %14$s %15$s "
        + "%16$s %17$s %18$s";


    int datetimecols[] = {5};
    int datecols[] = {17};
    String cols;
    int numColumns;
    int totalcolwidth = 0;

    List<String> columnNames;
    List<TypeInfo> columnTypes;

    ArrayList<String> row;
    StructObjectInspector rowOI;

    Object[] outputFields;
    Text outputRowText;


@Override
    public void initialize(Configuration conf,Properties tbl) throws SerDeException {
        LOG.debug("Initializing SerDe");
        // Get column names
        String columnNameProperty = tbl.getProperty(serdeConstants.LIST_COLUMNS);
        String columnTypeProperty = tbl.getProperty(serdeConstants.LIST_COLUMN_TYPES);
        LOG.debug("Columns : " + columnNameProperty + "Types : " + columnTypeProperty);

        if(columnNameProperty.length() == 0) {
             columnNames = new ArrayList<String>();
        }
        else {
             columnNames = Arrays.asList(columnNameProperty.split(","));
        }

        columnTypes = TypeInfoUtils.getTypeInfosFromTypeString(columnTypeProperty);

        assert columnNames.size() == columnTypes.size();
        assert colwidths.length == columnNames.size();

        numColumns = columnNames.size();

        for(int i = 0; i < numColumns; i++) {
             totalcolwidth += i;
        }

        List<ObjectInspector> columnOIs = new ArrayList<ObjectInspector>(columnNames.size());

        for (int i = 0; i < numColumns; i++) {
             columnOIs.add(PrimitiveObjectInspectorFactory.javaStringObjectInspector);
        }

        rowOI = ObjectInspectorFactory.getStandardStructObjectInspector(columnNames,columnOIs);

        row = new ArrayList<String>(numColumns);

        for(int i = 0; i < numColumns; i++) {
            row.add(null);
        }

        outputFields = new Object[numColumns];
        outputRowText = new Text();
}


@Override
    public Object deserialize(Writable blob) throws SerDeException {
         // TODO Auto-generated method stub
        Text rowText = (Text) blob;
        int index = 0;

        if(rowText.toString().length() < totalcolwidth) {
             return null;
        }

        if((rowText.toString().substring(0,1) == "H") || (rowText.toString().substring(0,1) == "T")) {
            return null;
        }

        for(int i = 0; i < numColumns; i++) {
            int len = colwidths[i];
            String col = rowText.toString().substring(index,index + len);
        // Convert the datetime string into the correct format so that it can be uploaded to the hive table
            if(Arrays.asList(datetimecols).contains(i)) {
                 DateTimeFormatConverter dtc = new DateTimeFormatConverter();
                try {
                    col = dtc.convertCurrToNew(col);
                } catch (ParseException e) {
                    LOG.error("Unable to parse Date Time string : " + col);
                    e.printStackTrace();
                }
            }
            if(Arrays.asList(datecols).contains(i)) {
                 DateFormatConverter dtc = new DateFormatConverter();
                try {
                    col = dtc.convertCurrToNew(col);
                } catch (ParseException e) {
                    LOG.error("Unable to parse Date String : " + col);
                    e.printStackTrace();
                }
            }
            row.set(i,col);
            index += len;
        }

        return row;
    }


@Override
    public ObjectInspector getObjectInspector() throws SerDeException {
        return rowOI;
    }


    @Override
    public SerDeStats getSerDeStats() {
        // TODO Auto-generated method stub
        return null;
    }

@Override
    public Class<? extends Writable> getSerializedClass() {
        return Text.class;
    }


    @Override
    public Writable serialize(Object obj,ObjectInspector objInspector) throws SerDeException {
        if(outputformat == null) {
            throw new SerDeException("Cannot write into table because no output format was specified");
        }

        StructObjectInspector outputRowOI = (StructObjectInspector) objInspector;
        List<? extends StructField> outputFieldRefs = outputRowOI.getAllStructFieldRefs();

        if(outputFieldRefs.size() != numColumns) {
            throw new SerDeException("Output format does not have the same number fields as the number of columns");
        }

        for(int i = 0; i < numColumns; i++) {
            Object field = outputRowOI.getStructFieldData(obj,outputFieldRefs.get(i));
            ObjectInspector fieldOI = outputFieldRefs.get(i).getFieldObjectInspector();

            StringObjectInspector fieldStringOI = (StringObjectInspector) fieldOI;


            outputFields[i] = fieldStringOI.getPrimitiveJavaObject(field);
        }

        String outputRowString = null;

        try {
             outputRowString = String.format(outputformat,outputFields);
        } catch (MissingFormatArgumentException e) {
             throw new SerDeException("The table contains " + numColumns + "columns but the output format requires more",e);
        }

        outputRowText.set(outputRowString);

        return outputRowText;
     }

}

您可以放心,我已经导入了需要导入的每个类.

当我尝试创建表时,我收到一条错误消息“无法从serde获取字段：my.hive.customserde.FIASC2”

这是堆栈跟踪

2015-08-25 15:57:51,995 ERROR [HiveServer2-Background-Pool: Thread-57]: metadata.Table (Table.java:getCols(608)) - Unable to get field from serde: my.hive.customserde.FIASC2
java.lang.NullPointerException
    at org.apache.hadoop.hive.metastore.MetaStoreUtils.getFieldsFromDeserializer(MetaStoreUtils.java:1257)
    at org.apache.hadoop.hive.ql.metadata.Table.getCols(Table.java:605)
    at org.apache.hadoop.hive.ql.metadata.Hive.createTable(Hive.java:694)
    at org.apache.hadoop.hive.ql.exec.DDLTask.createTable(DDLTask.java:4135)
    at org.apache.hadoop.hive.ql.exec.DDLTask.execute(DDLTask.java:306)
    at org.apache.hadoop.hive.ql.exec.Task.executeTask(Task.java:160)
    at org.apache.hadoop.hive.ql.exec.TaskRunner.runSequential(TaskRunner.java:88)
    at org.apache.hadoop.hive.ql.Driver.launchTask(Driver.java:1653)
    at org.apache.hadoop.hive.ql.Driver.execute(Driver.java:1412)
    at org.apache.hadoop.hive.ql.Driver.runInternal(Driver.java:1195)
    at org.apache.hadoop.hive.ql.Driver.run(Driver.java:1059)
    at org.apache.hadoop.hive.ql.Driver.run(Driver.java:1054)
    at org.apache.hive.service.cli.operation.SQLOperation.runQuery(SQLOperation.java:154)
    at org.apache.hive.service.cli.operation.SQLOperation.access$100(SQLOperation.java:71)
    at org.apache.hive.service.cli.operation.SQLOperation$1$1.run(SQLOperation.java:206)
    at java.security.AccessController.doPrivileged(Native Method)
    at javax.security.auth.Subject.doAs(Subject.java:422)
    at org.apache.hadoop.security.UserGroupInformation.doAs(UserGroupInformation.java:1657)
    at org.apache.hive.service.cli.operation.SQLOperation$1.run(SQLOperation.java:218)
    at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511)
    at java.util.concurrent.FutureTask.run(FutureTask.java:266)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
    at java.lang.Thread.run(Thread.java:745)
2015-08-25 15:57:51,996 ERROR [HiveServer2-Background-Pool: Thread-57]: exec.DDLTask (DDLTask.java:failed(520)) - org.apache.hadoop.hive.ql.metadata.HiveException: java.lang.NullPointerException
    at org.apache.hadoop.hive.ql.metadata.Hive.createTable(Hive.java:720)
    at org.apache.hadoop.hive.ql.exec.DDLTask.createTable(DDLTask.java:4135)
    at org.apache.hadoop.hive.ql.exec.DDLTask.execute(DDLTask.java:306)
    at org.apache.hadoop.hive.ql.exec.Task.executeTask(Task.java:160)
    at org.apache.hadoop.hive.ql.exec.TaskRunner.runSequential(TaskRunner.java:88)
    at org.apache.hadoop.hive.ql.Driver.launchTask(Driver.java:1653)
    at org.apache.hadoop.hive.ql.Driver.execute(Driver.java:1412)
    at org.apache.hadoop.hive.ql.Driver.runInternal(Driver.java:1195)
    at org.apache.hadoop.hive.ql.Driver.run(Driver.java:1059)
    at org.apache.hadoop.hive.ql.Driver.run(Driver.java:1054)
    at org.apache.hive.service.cli.operation.SQLOperation.runQuery(SQLOperation.java:154)
    at org.apache.hive.service.cli.operation.SQLOperation.access$100(SQLOperation.java:71)
    at org.apache.hive.service.cli.operation.SQLOperation$1$1.run(SQLOperation.java:206)
    at java.security.AccessController.doPrivileged(Native Method)
    at javax.security.auth.Subject.doAs(Subject.java:422)
    at org.apache.hadoop.security.UserGroupInformation.doAs(UserGroupInformation.java:1657)
    at org.apache.hive.service.cli.operation.SQLOperation$1.run(SQLOperation.java:218)
    at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511)
    at java.util.concurrent.FutureTask.run(FutureTask.java:266)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
    at java.lang.Thread.run(Thread.java:745)
Caused by: java.lang.NullPointerException
    at org.apache.hadoop.hive.metastore.MetaStoreUtils.getFieldsFromDeserializer(MetaStoreUtils.java:1257)
    at org.apache.hadoop.hive.ql.metadata.Hive.createTable(Hive.java:695)
    ... 21 more

我知道表创建失败了.但有谁知道我为什么会收到此错误？我试过谷歌搜索,但没有得到很多帮助.

如果它有任何帮助,这里是我正在使用的创建表脚本.

create table if not exists fiasc2(
record_type varchar(1),fin_id varchar(16),corp_id varchar(8),merc_id varchar(16),term_id varchar(8),tran_time timestamp,cashcard_number varchar(16),ttc varchar(8),tcc varchar(8),tran_type varchar(2),tran_amount varchar(16),deposit_amount varchar(16),pan varchar(32),account_type varchar(2),response_code varchar(2),card_balance varchar(8),settlement_date date,tran_mode varchar(1))
row format serde 'my.hive.customserde.FIASC2'
location '/user/hive/fiasc2_test';

解决方法

听起来很熟悉.
你正在返回null SerDeStats,这是我见过的唯一可能是null的东西,它响了铃,我想我的JSON SerDe在他们介绍SerdeStats几个版本的hive时遇到了同样的问题.
尝试：

// add this to the members
private SerDeStats stats;
// ...
public void initialize(Configuration conf,Properties tbl) throws SerDeException {
..
 // add this in initialize()
 stats = new SerDeStats();

// and of course here
@Override
public SerDeStats getSerDeStats() {
    return stats;
}

（编辑：李大同）

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