http断点续传简单实现（java)

/* yZ  P
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**SiteFileFetch.java ,L^L uw'7  
*/ Z*Y?"1ar  
package NetFox; iVl"H@m
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import java.io.*; N;hq  
import java.net.*; uI%[1`2N-  
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public class SiteFileFetch extends Thread { B\mdOTLQ  
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SiteInfoBean siteInfoBean = null; //文件信息Bean p\HXE4d'  
long[] nStartPos; //开始位置 2<O hO ^  
long[] nEndPos; //结束位置 R'3i
{ 1  
FileSplitterFetch[] fileSplitterFetch; //子线程对象 E=B9FIx~<  
long nFileLength; //文件长度 *kIJv?%_}  
boolean bFirst = true; //是否第一次取文件 N;w1f"V}  
boolean bStop = false; //停止标志 qd.b&i  
File tmpFile; //文件下载的临时信息 J2R<'(  
DataOutputStream output; //输出到文件的输出流 "-Ns1A8  
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//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） " c]Mz&z  
public SiteFileFetch(SiteInfoBean bean) throws IOException Z4e?zY  
{ 8O7JuR  
siteInfoBean = bean; `b2I)xC#  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); n-\B z.  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); |fA[s7)  
if(tmpFile.exists ()) s810714  
{ B|%;(bM2C  
bFirst = false; qle\c[UM5  
read_nPos(); @fY!@xSf  
}
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else pUPb+:^R  
{ <ya3|ycnS  
nStartPos = new long[bean.getNSplitter()]; *7R3EUUk  
nEndPos = new long[bean.getNSplitter()]; 5p>a]gp  
} z(]*'0)P  
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} 0#q_LB  
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public void run() 5P! ZJ3C  
{ m
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//获得文件长度 XJlun l)(K  
//分割文件 $nVTN.k  
//实例FileSplitterFetch V^0*S=N
 
//启动FileSplitterFetch线程 $'&5gFr9  
//等待子线程返回 vxwctJ&  
try{ }:BF3cH> 0  
if(bFirst) USbiI%   
{ 06ueE\@Sg  
nFileLength = getFileSize(); )~5`A*Ku  
if(nFileLength == -1) e88JT_zrO  
{ Y,8M[UIK  
System.err.println("File Length is not known!"); $HH(8NoL  
} *s!8BwiE  
else if(nFileLength == -2) _ x7Vyy5  
{ "#9WF}  
System.err.println("File is not access!"); WOwIJrP  
} lfGiw^  
else 3!d|K%J  
{ uM\~*@
  
for(int i=0;i<nStartPos.length;i++) x=H*"L=  
{ ja:%j&:  
nStartPos = (long)(i*(nFileLength/nStartPos.length)); 1{,WY(,c  
} Mpj3<vj   
for(int i=0;i<nEndPos.length-1;i++) ~@-Az([H  
{ A$ S9 `  
nEndPos = nStartPos[i+1]; L*5&hPU  
} Og,,s{
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nEndPos[nEndPos.length-1] = nFileLength; u'N'<(\k  
} 9 ROKueP  
} ~MXPiZG?  
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//启动子线程 O,bj_CWx  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; 5!5P\o  
for(int i=0;i<nStartPos.length;i++) :he
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{ }^QY<Cp|  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), lP@9%L  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), 9M7{.XR,  
nStartPos,nEndPos,i); g<,|Q5bK  
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); ZSbD4 |_  
fileSplitterFetch.start(); TX*P*-'  
} 8n'C@#{WV  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), )zz"DH  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); sMs 0*B-[  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", }9:d(B9;  
nEndPos = " + nFileLength); g.i
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// fileSplitterFetch[nPos.length-1].start(); SHIK=&\~-  
Bd31> %6  
?2aglj*"v,  
//等待子线程结束 118A6qyi  
//int count = 0; T%VC$u4F  
//是否结束while循环 3l-8TR  
boolean breakWhile = false; !QSL8v@c  
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while(!bStop) [59_n{S 1  
{ LS?3 >1g  
write_nPos(); ;Ze}i/l  
Utility.sleep(500); ?FA} ;?v  
breakWhile = true; nulVQOj|  
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for(int i=0;i<nStartPos.length;i++) %8DU}}Rj  
{ ,KdDowc  
if(!fileSplitterFetch.bDownOver) e)zE*9  
{ 9B{,q6  
breakWhile = false; ;1'X_tp  
break; XBh0=E?qiS  
} ;wa-\Z  
} AD_")_B|i  
if(breakWhile) Rr{mD#+  
break; tMR&>hM  
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//count++; w/IYQC\v  
//if(count>4) <v>^#/.
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// siteStop(); -Wd2FD^x  
} ZUyG }6)J  
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System.err.println("文件下载结束！"); ;:4&nJ*qG  
} l=GcgxD+"d  
catch(Exception e){e.printStackTrace ();} T~8==Z{[  
} O3/][\  
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//获得文件长度 #^4p(eZ[}  
public long getFileSize() eyUguA<lK\  
{ z$4g9  
int nFileLength = -1; Kkcb'a
DR  
try{ O]3$$uI=QE  
URL url = new URL(siteInfoBean.getSSiteURL()); #.L9/b(  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); wI8  
httpConnection.setRequestProperty("User-Agent","NetFox"); e=Ko4Ao2y  
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int responseCode=httpConnection.getResponseCode(); 55q!2>Jh.  
if(responseCode>=400) -@L7!,j  
{ nsn  
processErrorCode(responseCode); fIe';a  
return -2; //-2 represent access is error i^T@jg+K  
} diHK  
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String sHeader; JYbsta  
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for(int i=1;;i++) S!WG|75B  
{ 3 @ahN2  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); I
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//Utility.log(in.readLine()); vT@*o=I  
sHeader=httpConnection.getHeaderFieldKey(i); qlSI|@CO  
if(sHeader!=null) wnUuoX(  
{ 3bYPi^  
if(sHeader.equals("Content-Length")) q)j b9e   
{ @}; vl  
nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); ]31>0yj[Q  
break; dCA| )  
} )7]la/0  
} 5 EhOvt8  
else mrmm@?  
break; .A6D&-&z  
} tTEw"DL_-  
} -al\*XDz  
catch(IOException e){e.printStackTrace ();} j]HzI{7y  
catch(Exception e){e.printStackTrace ();} =/5^/vwgY  
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Utility.log(nFileLength); )J^5?A  
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return nFileLength; rU4;yy*b  
} p=!12t  

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//保存下载信息（文件指针位置） %$Dn);6=  
private void write_nPos() S>Z07d6&  
{ Nl]_Ie6  
try{ |)VNf.aJZ  
output = new DataOutputStream(new FileOutputStream(tmpFile)); HPMj+xH  
output.writeInt(nStartPos.length); uG7?:) pxv  
for(int i=0;i<nStartPos.length;i++) YsO3( HS  
{ n'To:  
// output.writeLong(nPos); ?;]Xc~  
output.writeLong(fileSplitterFetch.nStartPos); u>ZH-nw O  
output.writeLong(fileSplitterFetch.nEndPos); / Q| Z&-c  
} R XN0v@V  
output.close(); S awf]/  
} 3xk-D &"  
catch(IOException e){e.printStackTrace ();} =AcK9?%5  
catch(Exception e){e.printStackTrace ();} cYgd1  
} U?%T~!  
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//读取保存的下载信息（文件指针位置） A]laS7Q  
private void read_nPos() Cxd^i  
{ =pZ$oTR  
try{ .sjv"D"  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); %I=/ y  
int nCount = input.readInt(); NQxx_3*4O  
nStartPos = new long[nCount]; e?7y$H-  
nEndPos = new long[nCount]; qZdA%  
for(int i=0;i<nStartPos.length;i++) \_(|$Dhq  
{ H:nO\]  
nStartPos = input.readLong(); d]USk&8  
nEndPos = input.readLong(); OI_Px3) y  
} 5yyc0UG  
input.close(); .,sbqL  
} Wf3{z D~  
catch(IOException e){e.printStackTrace ();} ^-LnO%h?  
catch(Exception e){e.printStackTrace ();} Q4Nut  
} Q\
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private void processErrorCode(int nErrorCode) ^6gEL~m|]  
{ d}aMdIF!e  
System.err.println("Error Code : " + nErrorCode); {Mb2X^@7  
} iGSF5S  
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//停止文件下载 Q;ZV`D/FA  
public void siteStop() Pv=]7>e  
{ H
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bStop = true; .+mP#<mAg  
for(int i=0;i<nStartPos.length;i++) j<QK1d17  
fileSplitterFetch.splitterStop(); pHowioFx  
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} r:PYAb=g  
} \PD%=
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//负责部分文件的抓取 2c51kG77E  
**FileSplitterFetch.java lD'^6
 
*/ ^?_MIS`4N  
package NetFox; A>,kmU5  
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import java.io.*; Xq_hC"s  
import java.net.*; OJ7Uh_;/  
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public class FileSplitterFetch extends Thread { $WE=u9m  
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String sURL; //File URL Zx`/88!x[  
long nStartPos; //File Snippet Start Position 4`'Rm/)  
long nEndPos; //File Snippet End Position 6kMEm)YjT  
int nThreadID; //Thread's ID {t4':{Y+  
boolean bDownOver = false; //Downing is over @My RcC  
boolean bStop = false; //Stop identical aO}p"-'  
FileAccessI fileAccessI = null; //File Access interface xb"e'Zh  
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException N"0>)tG  
{ ny!80I  
this.sURL = sURL; ,Y#f0  
this.nStartPos = nStart; <WbO&;%  
this.nEndPos = nEnd; z =\ENG|x#  
nThreadID = id; s0CDp"uJY  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 >s!k"s,  
} mwn$ey&QE  
/XA*:8~!  
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public void run() o.Bbb=*rZ  
{ N/b$S@  
while(nStartPos < nEndPos && !bStop) :o87<) _F  
{ E(z|LS*3  
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try{ I)9,  
URL url = new URL(sURL); h#dfhcU>  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); (WP^}V5  
httpConnection.setRequestProperty("User-Agent","NetFox"); Jh36NE8r  
String sProperty = "bytes="+nStartPos+"-"; Qs?p)3qp  
httpConnection.setRequestProperty("RANGE",sProperty); naA8RD5/  
Utility.log(sProperty); '*Tt$
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InputStream input = httpConnection.getInputStream(); bYX.4(R  
//logResponseHead(httpConnection); uJ fXe  
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byte[] b = new byte[1024]; 32y 9
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int nRead; 
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while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) Okd.  ~  
{ %h;1}SFl0  
nStartPos += fileAccessI.write(b,0,nRead); jLY$P<u?%P  
//if(nThreadID == 1) &m]jYvRc  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); q0['!G%["  
} 5`lVC$cP  
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Utility.log("Thread " + nThreadID + " is over!"); *+00  
bDownOver = true; NO/5pz}1  
//nPos = fileAccessI.write (b,0,nRead); \.GA"_y  
} ?k@;,l :s  
catch(Exception e){e.printStackTrace ();} RMid}BRE  
} SLH;iqPT  
} W'Y(@  
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//打印回应的头信息 _Kh8 <$h  
public void logResponseHead(HttpURLConnection con) I*g[Y=  
{ O*n@!ye  
for(int i=1;;i++) 2E!Q5 l!j  
{ hvA|d=R(  
String header=con.getHeaderFieldKey(i); xJFcW+  
if(header!=null) {h.j6  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); xK5~9StP  
Utility.log(header+" : "+con.getHeaderField(header)); znIS2{p/`  
else [o7Qr?RN  
break; g@>93j=cZU  
} s"2+H}u   
} v_pFI8Cz)  
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public void splitterStop() vfc,{F=Q  
{ LW9
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bStop = true; $U)nrni  
} pTncx%!W5  
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} am7~  
_~}2@&*G"  

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/* hrXk7}9  
**FileAccess.java SDk^fTV8x  
*//文件访问(定位，写)
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package NetFox; 1?Tj  
import java.io.*; p9S>H  
T#[#w*w/  
 NfmHa  
public class FileAccessI implements Serializable{ i|28:FJA  
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//RandomAccessFile类用于在任意一个文件的特定位置上读/写字节 L@ejFXQg  
RandomAccessFile oSavedFile; x,fL656t  
long nPos; rfr]bq5  
)HX(-"c  
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public FileAccessI() throws IOException o,@(]e~  
{ HK%W7i/k@  
this("",0); 'T;;-M3*  
} -MFePpUt  
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public FileAccessI(String sName,long nPos) throws IOException .nEiYS|T  
{ cIP%t pTW.  
oSavedFile = new RandomAccessFile(sName,"rw"); bL+}n8B  
this.nPos = nPos; wt
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oSavedFile.seek(nPos); vcaPd}nf  
} s=556  
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public synchronized int write(byte[] b,int nStart,int nLen) H5o=nWQ6e  
{ wzBw5nf\  
int n = -1; 9`M7
-{  
try{ J"TF@7{p  
oSavedFile.write(b,nStart,nLen); ,,BWWFg~  
n = nLen; M5L/3qLh1  
} kv;P2:"|  
catch(IOException e) tg\o"QKW9  
{ ru
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e.printStackTrace (); DKkilqV
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} v-/vj/4>  
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return n; H8 xhE~'t  
} ''3I0X*!  
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} !Lw]aHb  
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/* 90K&oof?M  
**SiteInfoBean.java HxcL3Bh$~}  
*/ ./L)BLC i  
package NetFox; TwI'XMO;A  
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public class SiteInfoBean { =|8hG*D8  
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private String sSiteURL; //Site's URL 3dSC`K  
private String sFilePath; //Saved File's Path %l6E0[  
private String sFileName; //Saved File's Name 9
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private int nSplitter; //Count of Splited Downloading File iq[IZdza  
=%7s0l3z  
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public SiteInfoBean() _x|.\j  
{//nSplitter的缺省值为5 ,>8w|951'  
//default value of nSplitter is 5 51y#AQ@  
this("","","",5); s~9n13z  
} K1Uq`TJ  
1@JusS0^K  
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public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) R=F_U  
{ Bv'%$}}-  
sSiteURL= sURL; wy0?*)~  
sFilePath = sPath; C/'w  
sFileName = sName; VpSpj/\m)'  
this.nSplitter = nSpiltter; 4e#$-V   
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} 9dBxCdpu  
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7GWOJ^)  
public String getSSiteURL() Q2uV/M1?  
{ \C h01LR"  
return sSiteURL; K,$rG%czX  
} d7 H*F  
u+KZ. n/  
?s3S$Ih  
public void setSSiteURL(String value) b*M?\ aA  
{ ?Rx(@  
sSiteURL = value; 0GXY2+p}S  
} fe,6YXUf  
v{fcQb  
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public String getSFilePath() aR/?YKA  
{ )<:TpMdUk  
return sFilePath; [!-gb+L  
} i>s  
``Q6R2[|)  
<7`zc7c]#  
public void setSFilePath(String value) VL$ T  
{ mpMAhm
:  
sFilePath = value; Zrr)<'!i  
} HOF$(86zqA  
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public String getSFileName() Qop,~yK  
{ "8{A4N1B5  
return sFileName; G~YZ(+V%~  
} 'in%Gii  
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I/MY4?(T  
public void setSFileName(String value) ]
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{ P<<+;']  
sFileName = value; 7MLLx#U  
} [eDrjf3m  
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public int getNSplitter()  JhFbze>  
{ <f>w"r  
return nSplitter; {E:`  
} iM)K:L7d  
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bOFzq>k_  
public void setNSplitter(int nCount) ?K>)bA&l'  
{ m-
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nSplitter = nCount; xR/CP.dg  
} :ZV|8xI  
} >.d/@3 '  
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/* %8Ff
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**Utility.java CO='[1"_5  
*/ E EDFyZ  
package NetFox; 7~e,"^>T
 
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public class Utility { J:yv82  
rexv)!J  
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public Utility() 9\_AB.Z:  
{ .N X9Ab  
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} |LZ;2 i  
>GGM76vB=,  
//线程睡眠 'x*C#mt  
public static void sleep(int nSecond) Kjd3!%4mB  
{ yE8D^M|g  
try{ pl`4&y%Me  
Thread.sleep(nSecond); IA2VesHb  
} o08WC'bX  
catch(Exception e) I2[Z0G@&=  
{ atTR6%!6  
e.printStackTrace (); .l1
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} \f9WpAY  
} r3'J{-kl  
U>2KjZB  
//日志 qU
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public static void log(String sMsg) o[ZjXLJzV  
{ *D?=Ts  
System.err.println(sMsg); {A0jkU  
} DBAyc#&#  
z%8`F%2  
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public static void log(int sMsg) ET}Z>vU}+  
{ {-4+=7Sg1  
System.err.println(sMsg); m!FuC=e  
} rN}pi@  
} MQoA\  
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/* C
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**TestMethod.java aopPv&jY  
*/ wA5Iz{uQ
O  
package NetFox; UIAazDyC  
rCPIz<  
jFN0xGZ  
public class TestMethod { ;M~,S^U  
h#YO;m2wd  
5A0]+)5E8  
public TestMethod() syX?O'xJ  
{ ///xx/weblogic60b2_win.exe v9f+ {Y%-  
try{ "'v+*H 3  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); M/o?D <'  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); &#PPXwmR  
SiteFileFetch fileFetch = new SiteFileFetch(bean); >=N-P<%  
fileFetch.start(); z*},N$2=  
} h@ lz  
catch(Exception e){e.printStackTrace ();} /|v4]t-  

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} E)*ht;u  
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public static void main(String[] args) DtANb^  
{ gv67+Mf  
new TestMethod(); _HwA%=>7  
} ys`-QlkB  
}
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